I purchased my HD-70FH96 in early 2006 and it's still going strong! I just ordered a new lamp for it (for local pickup at Discount-Merchant). It's a genuine Phillips lamp and it was $79.99. Amazing that the lamp prices are actually going down instead of up!
This will be the fifth lamp in nearly 8 years. I never wait until the lamps blow out or for a lamp replacement warning to pop up. As soon as I notice the screen seems a bit too dim, I get a new lamp. I've got several "backup" lamps that have a bit of life left in them for an emergency situation (should a current lamp fail suddenly).
The only issue I've had with this TV is the freakin' spiders that want to get inside the thing. Every once in awhile, bug parts end up getting settled on the lens. Rather than pull out the entire light engine chassis (from the rear} or take off the entire screen, I've learned I can just remove the lower speaker grill and the little door behind it to gain partial access to the area around the lens. Then I use a bent tube on the end of a compressed air can to spray debris off the surface of the lens. Works great for a quick and easy clean that can be done in about 5-10 minutes.
But, each time I do put in a new lamp I do pull off the entire front screen and give both the lens and mirror a good cleaning (and use my vacuum to suck up spider webs, bug debris and dust. When I'm all done and put up a solid light blue image on screen, I can still see a few small spots of cloudiness here and there. I've determined that it's dust/debris in the light path in the light engine. I've not tried to disassemble the light engine because of a lack of any good video tutorials. It would be terrific if I could get the dust and debris out of the light path, but it's really not a big deal. It's only noticeable in very white or other light colored scenes. (If anyone knows of a video or tutorial explaining how to disassemble and clean the sealed light path, please share.)
I'm hoping to get another year or two out of my HD-70FH96. I continue to feel that LCoS rear projection makes a better and more film-like image than either plasma or LCD. But I know that I'll eventually have to get a set that uses a newer technology. I have to admit that I've been eyeballing the 75" Samsung models!
Of course, the big upside is that spiders and bug debris should become a thing of the past with the newer tech!