i put the Epsi in the effects loop, and placed the loop right after the amp model. then i turned off the 11R speaker and used just the loop for a cabinet. set effects loop input about 9:00 so it doesn't clip, output about 3:00, and mix to 100%.
the Epsi has killed some Axe-fx gas for me (for now). if you are a meat and potatoes tone guy, then the Epsi is the answer. if you are an effect junky, then only the axe-fx will satisfy.
Honestly, you could put a cheap distortion pedal in front of the Epsi and get a decent tone.