The point about the depth of the storm & the upper-level conditions is largely the big one at play here. I don't have a map handy, but I'm willing to bet that the upper-level temperatures above Epsilon are colder-than-normal, particularly for the given SST. It can't draw a lot out from the ocean, due to the lower temperatures, but what it is getting it is making pretty efficient use of -- this is a part of the heat engine depiction of the tropical system and the so-called maximum potential intensity theory (http://wxmaps.org/pix/hurpot.html). Epsilon's left the most favorable region for maintaining itself as a hurricane and is probably nearing the limits of what it can do until it turns back SW (if the ideal conditions were maintained, which they likely won't be)...we'll see what happens from here.