I used exoSAP Digestion before Big Dye labelling and capillary sequencing. It worked fine. (15 minutes 37°C and 15 minutes heat inactivation). For Digestion I never used any purification kits. Do you want to do 3 different digestion in the same PCR product or on three different products (each one)?

Exosap and the column-based kit are on equal footing in regards to results, with Exosap being the more comfortable, and thus more expensive way to do it. I can recommend using it if you have the funds. Something that may help is that you can use a lot less of it than what is given in the manual, and will still work. We use 1 µl per 5 µl of PCR product (though that also depends on how big your primer clouds are), I have colleagues who go down to 0.8 µl/5µl.

i have used exosapit for purification of PCR product for sequencing. i worked on restriction digestion also but i didn't used exosapit in digestion. you can go directly to digestion even if you have primer dimer in your gel it will be below your digested product size,. 

Are you doing tRFLP? In this case a simple ethanol/EDTA precipitation should work fine for restriction digests.

Hello, do you have used EXOSAP for T-RFLP?