Unfortunately, the UE 900 never really do completely fix the problem they have with vocals. They don't get to the highest areas they should (but still amply get up enough), and they definitely lack in intimacy and warmth, emotion as you stated, which sets them back a bit (if there was one thing to change on the UE 900, it's this IMO) :(
Quick warning about blocking the pinhole bore, it will make the UE 900 much more dry and sterile. Seeing your past IEMs (SM3 is the only one I've read up on, haven't listened to either), it may not be the direction you want to go. I think Rin described it as being able to match the linearity of the ER4 (with 100 ohm adapter). If that's not the direction you want to go, you may not want to plug that hole up :p
Hmmm... sounds like they may be ripe for a return. There is a lot to like with them but I don't know that I can live with the deficiencies at this price point. I may grab some 535's but slap on a UE900 blue cable if I can find one.