I haven't read most of the thread so i don't know if this has been mentioned but the PS3 that are messing up are the 60 gig ones. I haven't heard of the others failing that badly. The 60gigs are older and not made anymore so that could be why. And i have a 60 gig i hope it keeps working, knock on wood.
The blue is a valid reason why they could be failing more.... but until more time passes we won't know if similar things will happen to other models when they get as old as the 60G is now.
The purple makes no sense.... they are not made anymore true, but that shouldn't affect how they were made 2 years ago, so unless 60G PS3s are concious entities that are commiting suicide because they are not being made anymore, it isn't a valid reason as to why they are breaking more than other models.
My suspicion is that 60G originals, with all the acctutriments will probably run a good bit hotter than newer models, so that will affect the life of the parts inside. So I suggest you keep it well ventilated, shaded, and don't play long hours of gaming on those heatwave days, which should lower the chances of anything happening to it.