Well, I took my HL-S6767W back to Costco today, and they refund me the full purchase price that I paid two years ago. The TV was $3968 out the door in July 2006 and that's what they gave me. I couldn't believe it.
So at this point I'm just going to go TV-less while I decide if I want the HL67A510 or go for the 67A750.
