It depends on the phase diagram of the part you are manufacturing; final microstructure is a key parameter in the part's mechanical strength and many other properties. The question can be better answered for a specific scenario of additive manufacturing when parameters such as material, temperature, etc. are specified.

Generally speaking, adding another phase to create a transient liquid phase during heat treatment/sintering can facilitate densification of AM materials.  By selecting the additives, it is possible to provide an AM material that can maintain dimensions during heat treatment.  It can also provide a useful solid solution strengthening effect.

The disadvantages of the transient liquid phase would be dependent on how the additives degrade the properties of the AM materials.

Thanks for sharing your precious ideas. 

Some other aspects related to this question are as follows,

Dimensional inaccuracy in AM parts due to thermal distortion is caused by non-uniform expansion and contraction of different regions of the part that experience changes in temperature. Thermal distortion during the deposition process depends on alloy properties, heat input, deposition time, substrate dimensions, part geometry, and time delay between the depositions of successive layers.

Lack of fusion is caused by inadequate penetration of the molten pool of an upper layer into either the substrate or the previously deposited layer. Inadequate penetration can cause voids to form in the final product.