I bought the e4c's at 1st, and for rock music, which i listen to primarily, they pretty much sucked the big one... any more than 3 instruments at one time and they sounded very strange (not really sure what the right term would be) but it sounded like the sound waves clashed and everything sounded warped.
I then bought the UM2s.
O...M...G...
they sound so awesome, its beyond words. The 1st song I listened to was "Welcome Home" by coheed and cambria, and my nose got all itchy, eyes got kinda foggy 'cuz these things sound so incredible.
Dont even get me started about what happened when I listened to the live orchestra version of 'one winged angel'
UM2s make my day, everyday.