I have the KDS-50A2000, bought on Black Friday almost exactly three years ago. The bulb blew suddenly last night, so I purchased a replacement today (My Sony ext. warranty does not cover bulbs). I wanted to know how many hours I had gotten before I reset the timer - service menu showed 4376 hours (exactly 4 hours/day on average). I'm a little disappointed with the short life, but a couple factors could have contributed - we do a lot of on/off cycling, and we had 3 power outages in the first 2 weeks we owned the set - before I had a chance to go out and get a UPS. We almost NEVER have power outages, but Murphy strikes again!
I do want to warn everyone about the difficulties of getting an immediate bulb replacement. These things can be hard to find, so if you're up to ~4000 hours I suggest you start shopping now to have one on hand when it blows.
Watch out for bait-and-switch tactics and other misleading claims. Because I did not want to do anything that could void my extended warranty, I absolutely wanted a genuine Philips bulb. I was willing to open the cage and swap the bulb myself, but I did not want any no-name brand, or even Osram, because if the ballast or OB went afterwards a service tech would immediately recognize the off-brand bulb and claim it contributed to the failure.
Compounding my difficulties, I wanted the bulb FAST - I was willing to pay for overnight shipping, or pay even a little more to find a local place to pick it up. But with my son coming home for the holidays and us having some rare free time to watch TV this weekend, I did not want to sit here for a week waiting for a new bulb to arrive. And with holiday shipping delays, that was a big risk.
I wasted the whole morning calling web-based sellers asking if they could meet my requirements. I need you to know there are a lot of sites out there claiming to have bulbs in stock that actually do not. And also ones who will claim, in multiple places, that their bulbs are genuine Philips, but are not. I spoke to about 6 different retailers whose websites claimed to have Philips bulbs in stock, and all of them were either out of stock, selling Osram bulbs, or wanted 48 hours to process my charge card, so were unwilling to ship product before next Monday (but more than happy to take extra $$$ to use overnight shipping to get it to me by Tuesday).
In the end I found a local web-based retailer who said they had genuine Philips bulbs without the cage. Their web page was titled "Philips DLP bulbs", and the word Philips displayed 44 times on that page - with no mention of Osram. They wanted $125 for this Philips bulb, which is a little higher than other web-based retailers, but they were local so it was worth a little extra. I called on the phone to confirm that they had the Philips bulbs in stock, made the purchase over the phone (because their warehouse was at a separate location) and hopped in the car to go pick it up. The lamp was in a plain brown box, different from the Philips box pictured on their Amazon.com listing. As I was driving away, I got a little suspicious, so I pulled over and opened the box. It was a #*$#& Osram bulb! I drove back and immediately returned it. The guy at the warehouse was (feigned?) surprised that the bulb was not Philips, and searched all over to try to find me a Philips one. One of the other guys told him they had recently stopped carrying Philips.
Disgusted at wasting the whole morning, I drove down to New Castle, DE, and forked over $200 for a genuine Sony bulb with cage from CB Joe TV. It was no longer worth the trouble to save some extra money. My set lookg great, and my kids will love me this weekend.
Once my extended warranty is toast, I'll give Osram a try if I can't find Philips. But until then I'm covered with the genuine Sony part. In about 2 years I'll go online to find a good deal on a bulb, and put it into the extra cage that I now have so I can have a spare ready to pop in next time my old bulb pops out.