I'm just helping out a buddy, as he torn between choosing between these two top custom earphones
I myself have the SM3, and can't hardly recommend anything better than the em3's should they sound better than the SM3's
He's had a listen to my SM3's and was blown away by the soundstage and natural sound without fatigue.
This is comparing with his W3's.
He was going to go the full custom route EM3pros, but after reading shigzeo's review http://www.touchmyapps.com/2010/04/18/acs-t1-custom-fit-iem-in-review/
The new silicon design looks great! It looks like, correct me if I'm wrong, but butter isolation compared with acrylic material, and the description of bass in the T1's sound awesome.
One thing if I could improve about the SM3's would be the bass department. It sounds good with music that has lots of sub bass, but with my house music, it doesn't sound fun.
I mean the bass is nice and punchy and in proportion to the music, but it doesn't have that sub woofer impact that is described in shigzeo's review
If anyone who has owned or has had a chance to listen to the two can comment about the differences, and soundstage that would be great!