My first 8500UB bulb blew around 1,800 hours after nothing but Eco mode use. Right before it blew, it did this weird random dimming thing like the iris was on... then one night, it went super dim and blew the next week during Return Of The King (seriously, right when Gollum falls into the fires of Mount Doom - POP!). Epson sent me out a new bulb with no problems.
That replacement bulb just hit 1,800 hours. Sure enough, about a week ago, it started doing the random dimming thing. Tonight, the bulb dropped in brightness noticeably, but is still working. I called Epson, told them what's happening and that I'm afraid this one's going to pop like the last one... and without the bulb even blowing yet (and with just over a month left on my warranty), they're overnighting me a replacement.
Say what you will about the quality control problems... but compared to my customer service experiences with Sanyo on my last projector, Epson is AMAZING. When it comes time to replace the 8500UB, it's a pretty safe bet that it will be with another Epson.