Well, sorry to say I have joined the ranks of Ex HP owners.
I had the 65" version for a little over 5 years, and loved the thing. There was the problem of heat and the posterization appearance after a few years of ownership, but I did solve that problem with additional air flow. Until the end, the TV provided an excellent picture.
In my case I had a five year extended warranty with Best Buy here in Canada. As the end of the warranty period approached, I decided it was best to exercise my option to get a full monetary refund for a flawed TV. I removed the additional TV cooling and arranged for a Best Buy tech to confirm the TV was bad'. The posterization appeared on cue and the tech said It's toast, and not repairable since parts are not available
The issue for many owners is clearly heat, and a mechanism for heat dissipation from the TV. Here's a photo of what I did.
I pumped air into the cardboard shroud using my basement bathroom fan. The fan power came from the switched outlet on my PVR, so that when the PVR was turned on, on came the fan. I added a dimmer switch to allow the fan speed to be adjusted (less air needed in the winter).
I did create a little web site about 5 years ago that included a link to the Service Manual for this DLP TV. I'll leave this up for those interested. http://www.cykf.net/hp_stuff.htm
I also have a brand new unused bulb, a bulb with a year and a half of use, and the remote control. I'll probably try to sell these on Ebay, but offer them here first. If anyone is interested, I'd be looking to sell these 3 items as a package for $200 plus postage.
Finally, many thanks to DarrellH for starting this entire thread, and to all the other contributors, who in my case, helped me solve my posterization issue, and allowed me to enjoy this TV as long as possible.