Yea, the reason I bought the warrenty on this was really because it did have mechanical parts to it, and a bulb. I got a decent deal, I think it was $150 for 5 years from date of purchase and at the time, I paid over 2k for the TV in Aug 2005(HLR-5667)
Of course it's held up pretty well, save a few little quirks. Still on the original bulb, brightness looks fine to me. I did have the digital board replaced under factory warrenty about 8 months after I got it, because it was shutting off on it's own.
I do like that flat panels don't really have any "mechanical" parts to them, and if something goes in them, it's not likely it's a simple cheap part, like many things in a car, for example. I'd be much less likely to buy a warrenty for an LCD or plasma with how "cheap" they have gotten. I won't buy another DLP again, despite the fact that mine has been pretty reliable.
The little things in this set like TVGOS(which I still use and it works), firewire inputs and CableCARD are IMPOSSIBLE to find in a modern HDTV. Impossible. That is what will make it hard to give up when the time comes.