I use either E2C's or Sony V6's as my portable phones, and one thing I've found that hasn't been mentioned: the type of music you listen to can make a big difference with the Shure's. I generally listen to heavy rock, and was fairly underwhelmed by the sound quality of the Shure's. They didn't sound bad, just not as good as I was expecting. A little while back I loaded some songs with a lot of acoustic guitar onto my Ipod, and was blown away. The guitar's on Jack Johnson's "On and On" sounded better than I have ever heard them, and I found myself playing tracks over and over again just to listen to the instruments. I'm not an audiophile by any stretch of the imagination, but I think a person's musical tastes could play a large part in their perception of the E2c's.
One other thing I've found is that the foam inserts sound much better than the silicon, in my opinion. They have a warmer sound, to my ears, and don't sound as hollow. I also find them much more comfortable.