Now I'm actually going back and forth on the Sony XBR-65X900B and the Samsung UN65HU8550.
The CNET review said the picture of the Sony is among the best they've ever tested, and I'm sure I'd appreciate the speakers since I've never had any dedicated sound system before, but I don't know if it's worth an extra $1,500 over the HU8550. You can preorder the HU8550 for Amazon's Black Friday event for $2,300, and the X900B is still sitting at $3,800, though I figure it'll drop at least a few hundred around Black Friday. I'm not an audiophile, the input lag as tested by the reviewer is the same, and the HU8550 actually got a slightly higher rating from the CNET editor than the X900B did, so I'm not sure which way to go with this.
Edit: Actually, it seems the Samsung unit's input lag is almost twice as high as Sony's according to several other sites, so I guess that made the decision easier.
It's not. The input lag of the Samsung is ~40ms as long as Game mode is on, basically same as the Sony I believe. Early reviews noted very high input lag (around 70ms) but it was lowered in a firmware update.