I was able to see an ST50 at BB last night. At first the sales guy tried to convince me that the UT50 was a better value and didn't even want to show me the ST. I persisted and he finally took me to the 3D kiosk where they had it on display and the he just started to lay in on the TV, telling me to look at the problems with the corners (from extreme angles). I didn't really understand this sales approach, but whatever.
It's a great picture (even with the limited content I was able to view), and the motion smoothing was hard to discern when activated even on "strong" Strange, because I thought it was supposed to give a pretty obvious soap opera effect. So I wasn't really allowed to play with it much, but I still think I want one.