Mine must be the fastest case of being "in the club" and out of it.
As you saw I purchased a 46XBR2 last night and had the backlight showing during dark scenes. So, today I hauled the beast back to CC and it turns out they had another one in stock. We set mine up and the new one in their (mostly) darkened home theater room in the back of the store. The first set was worse but the second set also had the issue. It was kind of embarassing as I am sure they thought I was being too picky, especially on the second set, but they were nice enough about it.
As I talked to the manager more about it, he took me out into the store and showed me a whole bunch of smaller (30+" to 40") Sony sets that all exhibit this to varying degrees. He claims it is simply par for the course for these sets. He says most people never notice it or just assume it is "normal". He said they have never gotten a set back for this reason before.
I was torn about getting a third set, they were willing to order another one and when it comes in open it for me again to check it out. I decided, however, to get a refund.
So, on my way home I go to BB to examine their XBR3 in the Magnolia room more closely as I thought it did not have this issue. Sure enough on closer examination it does have this problem as well. It is harder to see there as the Magnolia room is not quite dark, though darker then the normal TV area at my BB. One more stop at a local appliance store and they have both an XBR2 and a 3 and both also have this.
I am really really really tired of the research and trying to pick the right set. I don't think it exists for me at this point in the various technologies. However, I need to get something (mainly for my wife). I am probably going with a plasma (maybe smaller, 42") for now to please the SO and reinvestigate things next year.
Color me frustrated.