I know that I shouldn't jinks myself, but I own 2 phats (original 40GB, and 80GB MGS4 with some PS2 backwards compatibility).
These things don't owe me anything at this point. The 40GB phat has played every Bluray disc that wasn't cracked from Netflix and Blockbuster and the 80GB has so many gaming hours by my son that I can't believe it still read Game discs like it was new. It has played every PS3 game disc he has rented (blockbuster and local) except 1. The 80GB ps3 is also transported 6 times a year for vacations.
I have rented hundreds of Blurays since I have owned them.
My home has quality electrostatic dust filters on the furnace with regular circulation times scheduled and some standalone air filters. My home is always maintained below 75degrees. I wonder if heat kills peoples PS3s?