First of all we correctly refer to the term as UHPLC, not "UPLC" (that is a Waters trademark). Terminology is important in science. The big players are Agilent and Waters. Both have good systems capable of max pressures from 600 bars to over 1,000 bars.

"Ruggedness" does NOT depend on the brand of system used. Who told you this? Must have been a sales person! Nonsense. Normally, the skill level of the operator,  chosen method employed and techniques used determine ruggedness, not the brand of system used.

Hundreds of articles you can read on this topic. Vendors want you to buy a new LC system often so are biased towards this idea (caveat emptor). UHPLC is just the use of a sub 2 micron supports on a small column with a properly plumbed and optimized HPLC system. We have been doing this for decades using conventional HPLC systems with slightly larger diameter supports, between 2 and 5 microns, in narrow-bore columns (since the 1980's). However, many users still have not become proficient in how to use std columns and supports so the push to even smaller supports and columns has failed many times in the past (poor availability of columns with small supports, frequent clogs, gradient delays, poor programing of methods, poor batch-to-batch reproducibility of columns). In many cases, you can run these same types of separations on the very same HPLC system you have right now. Just optimize the flow path (esp. the injector, flow cell and pump) to reduce the total system dwell volume for gradients. Most methods are run at pressures below 400 bars so are compatible with most traditional systems (which max out at 400 or 600 bars). The key areas you need to address are: adjusting any gradient parameters to the new, lower volumes used and make sure that whichever HPLC system you use, the system delay volume is minimized/optimized and appropriate for the tiny column you will probably end up using (as in 'tiny internal volume'). This is needed to minimize diffusion and gradient delays which if ignored, will negatively impact your final results.

Pros: (1) A properly developed UHPLC method using these newer, tiny supports may result in the same or much better resolution as obtained on a std sized column, but in less run time and using less mobile phase. (2) Methods developed with the more reliable 2.5u particles in mid-sized columns are a nice compromise in solvent savings, shorter run times and easier re-development process. These can also be run on most conventional HPLC systems, which is a 'pro'.

Cons: (1) As of this writing, sub 2 micron supports are nowhere near as reliable and reproducible as standard supports (2.5-10u). It has proven very difficult to pack these tiny particles uniformly into any sized column. %RSD between columns of the same type often vary a great deal. This makes validation and practical use more difficult. (2) Vendors want you to buy a brand new system to run these on (when in fact, depending on the system you have, you may not need to). Expect to easily pay $50-100K USD or more for a basic system. (3) You will probably have to re-develop and/or re-validate every method that you wish to use from scratch to use the UHPLC version (since the column used will probably be outside the allowable guidelines for change). Depending on how this impacts you, it could result in enormous amounts of time and money spent. (4) Many re-developed UHPLC methods (e.g. in the literature, application notes) have been very poorly developed. I routinely see labs who use UHPLC methods that are worse than std methods. This is not the fault of  "UHPLC", it is what happens when poor training is combined with poorly set-up hardware. You still need to be skilled in method development to generate high quality methods with any column. UHPLC is not a short-cut to good/better methods. (5) Fewer overall column choices (though, this is improving). (6) UHPLC run at higher pressure wears out parts faster than conventional HPLC systems. Higher operating costs (the parts and service cost more). (7) Method transfer (Validated Methods) can have a much higher failure rate from one lab to another because their are dozens of critical parameters which can change from system to system. UHPLC methods should be designed to be even more rugged (more testing) to minimize the effects that ordinary method variations can have on the results.

I have also attached a variety of articles on this topic which I hope you find useful.

http://hplctips.blogspot.com/2015/08/terminiology-which-is-it-uplc-uhplc-or.html

http://hplctips.blogspot.com/2011/07/hplc-to-uhplc-conversion-notes.html

http://hplctips.blogspot.com/2014/10/appropriate-mixer-volume-for-hplc-and.html

http://hplctips.blogspot.com/2011/08/pressure-drop-across-hplc-uhplc-column.html

First of all we correctly refer to the term as UHPLC, not "UPLC" (that is a Waters trademark). Terminology is important in science. The big players are Agilent and Waters. Both have good systems capable of max pressures from 600 bars to over 1,000 bars.

"Ruggedness" does NOT depend on the brand of system used. Who told you this? Must have been a sales person! Nonsense. Normally, the skill level of the operator,  chosen method employed and techniques used determine ruggedness, not the brand of system used.

Hundreds of articles you can read on this topic. Vendors want you to buy a new LC system often so are biased towards this idea (caveat emptor). UHPLC is just the use of a sub 2 micron supports on a small column with a properly plumbed and optimized HPLC system. We have been doing this for decades using conventional HPLC systems with slightly larger diameter supports, between 2 and 5 microns, in narrow-bore columns (since the 1980's). However, many users still have not become proficient in how to use std columns and supports so the push to even smaller supports and columns has failed many times in the past (poor availability of columns with small supports, frequent clogs, gradient delays, poor programing of methods, poor batch-to-batch reproducibility of columns). In many cases, you can run these same types of separations on the very same HPLC system you have right now. Just optimize the flow path (esp. the injector, flow cell and pump) to reduce the total system dwell volume for gradients. Most methods are run at pressures below 400 bars so are compatible with most traditional systems (which max out at 400 or 600 bars). The key areas you need to address are: adjusting any gradient parameters to the new, lower volumes used and make sure that whichever HPLC system you use, the system delay volume is minimized/optimized and appropriate for the tiny column you will probably end up using (as in 'tiny internal volume'). This is needed to minimize diffusion and gradient delays which if ignored, will negatively impact your final results.

Pros: (1) A properly developed UHPLC method using these newer, tiny supports may result in the same or much better resolution as obtained on a std sized column, but in less run time and using less mobile phase. (2) Methods developed with the more reliable 2.5u particles in mid-sized columns are a nice compromise in solvent savings, shorter run times and easier re-development process. These can also be run on most conventional HPLC systems, which is a 'pro'.

Cons: (1) As of this writing, sub 2 micron supports are nowhere near as reliable and reproducible as standard supports (2.5-10u). It has proven very difficult to pack these tiny particles uniformly into any sized column. %RSD between columns of the same type often vary a great deal. This makes validation and practical use more difficult. (2) Vendors want you to buy a brand new system to run these on (when in fact, depending on the system you have, you may not need to). Expect to easily pay $50-100K USD or more for a basic system. (3) You will probably have to re-develop and/or re-validate every method that you wish to use from scratch to use the UHPLC version (since the column used will probably be outside the allowable guidelines for change). Depending on how this impacts you, it could result in enormous amounts of time and money spent. (4) Many re-developed UHPLC methods (e.g. in the literature, application notes) have been very poorly developed. I routinely see labs who use UHPLC methods that are worse than std methods. This is not the fault of  "UHPLC", it is what happens when poor training is combined with poorly set-up hardware. You still need to be skilled in method development to generate high quality methods with any column. UHPLC is not a short-cut to good/better methods. (5) Fewer overall column choices (though, this is improving). (6) UHPLC run at higher pressure wears out parts faster than conventional HPLC systems. Higher operating costs (the parts and service cost more). (7) Method transfer (Validated Methods) can have a much higher failure rate from one lab to another because their are dozens of critical parameters which can change from system to system. UHPLC methods should be designed to be even more rugged (more testing) to minimize the effects that ordinary method variations can have on the results.

I have also attached a variety of articles on this topic which I hope you find useful.

http://hplctips.blogspot.com/2015/08/terminiology-which-is-it-uplc-uhplc-or.html

http://hplctips.blogspot.com/2011/07/hplc-to-uhplc-conversion-notes.html

http://hplctips.blogspot.com/2014/10/appropriate-mixer-volume-for-hplc-and.html

http://hplctips.blogspot.com/2011/08/pressure-drop-across-hplc-uhplc-column.html