I have the Reverb unit in the FX Loop. I have the Cabinet IRs as well, but haven't tried it yet. From what I have read people didn't find much difference using the IR's that come with the EPSI, but loading IRs from other libraries might. I was planning to do the same with the Cab IR Pedal (in FX loop). I haven't figured out how to use both yet (I am thinking that I will put the Cab IR in front of the Reverb one, but I guess I will just have to try different combos). I have the FX loop for the Verb pedal at the end of the chain. Not sure how that will work with the Cab IRs. I am hearing conflicting opinions on whether to put the Cabs right after the amp models or after the post-amp effects.