I found a Best Buy in my area that carries the KDL-46HX850, amongst other models, including Panasonic and Samsung plasma displays. So I did some comparing and auditioned the HX850.
Honestly, I really felt the plasma displays were too limited in brightness for my taste, not to mention there are not too many available in a 46" size, which is what I'm limited to on my TV stand.
I demoed the HX850 watching Star Trek (2009). I was sold on that model as far as picture quality goes. They also had a XBR-46HX929 there, but I noticed some of the screen uniformity and blooming issues that some reviews have mentioned (CNet, Television Info, etc), plus I don't like the fact that manufacturers are forcing people away from analog (like this model for example), when it is not dead yet, so the HX929 is out. From what I have read, the HX909 from 2010 is better as far as uniformity and blooming goes, although the 3D isn't quite as good. But I wonder if the picture quality would be similar to the HX850?
The price tag is also part of my final decision, and the HX909 is available used in excellent condition on Ebay for $1150 with shipping (with a $140 optional warranty), but the HX850 is $1688 new with a manufacturer warranty. I also just tripped over a posting on Craiglist for an HX850 for $800, but this is only if the seller is willing to ship. I know the HX850 would be the way to go if the seller will ship.... but if he doesn't, which would you go for?