I just recently got the E2C and still am evaluating them. The sounds seems a little off to me. I can't put my finger on it exactly but things just sound a bit off, the instruments just don't sound right. Perhaps when they break in a bit, it'll sound better. This is in addition to the rolled off highs and muddy bass. I'm not planning on returning them because overall, they are pretty good (and hopefully will get better)
I've had the MX500s for years and actually prefer their sonic signature to the E2C. IMO, the MX500 has a less muddy bass and better mids and highs than the E2C (But my E2C, still being new, may open up a bit with use.). I got the Shures to fill the "unamped isolation" catagory (I have the Ety ER-4S for when I have my amp along) and the MX500 doesn't isolate at all. I do find the Shures very comfortable though, and can wear them for extended periods. Others compain about comfort which just shows that canal phones fit different people differently.
As for the SR225 (which I also have), there is no comparison with the E2C. After listening to the E2C for a while, putting the Grados on brings a really big smile to my face.
Michael