the Epsi is the real deal my friend. it will transform your 11R into a rig closer to the axe-fx. the biggest deal for me on the axe-fx was the ability to load an IR that sounded like a particular cabinet, or better yet....the sound of MY cabinet. the cabs in the 11R are actually quite good compared to other modelers out there, but they are no match for a good studio mixed IR. the 11R has one cab with one mic, on/off axis....that's it. in the real world, i would only mic a cabinet like that live, where people can't really tell how my real tone is. in the studio; i would use several mics to capture the best the cabinet has to offer.....and that's what Ownhammer did. i am currently using mic mixes from their modern collection and i am blown away by how good it sounds and feels. feel is a bigger deal to me than sound is. i can load up an IR that feels great to me, regardless of how it sounds, then reamp a choose the preset that sounds best. so i get to have it both ways. you can also get that amp in the room tone, which we all chase after.
if you are already happy with the 11R, which most of us were, then you don't really NEED the Epsi....but it is awesome to have.
the one thing the Epsi will do to you is take you down the rabbit hole of options that can paralyze you like the axe-fx does.
my advice (which i took) is to pick only 1 each of your favorite of any IR cab type (V30, scumback m75, scumback h75, greenback, etc) and use just it instead of going through 40 options every time you play. you will quickly learn that some cabs work well with certain amp types, and that's it.
for example:
scumback m75 - subdued highs and lows, works great for low gain rock.
scumback h75 - has more highs and lows than m75, good for 80's metal
V30 - mid peak - works well with all scooped designed amps like the Recto. general decent cab with most amps.
K100 - Djent and metal.
i plan on doing some demos of what cabs sound best with what amps. i have only gone thru maybe 60 or so of the cabs that i bought from Ownhammer, so i need to finish checking it all out soon.