I know it's an anecdote, but my neighbor's display has developed a bunch of stuck pixels in 3 years or so. Annoying. I don't know if that's a common issue, though. It used TI's original chipset, I don't know if it was licensed to other parties though, so that may be a moot point.
I've got the same problem on my 73" Mitsu DLP. The "acne" is a common problem due to a run of bad DLP chips. The mirrors stick. You can replace the DLP chip for $159 http://www.shopjimmy.com/samsung-mitsubishi-toshiba-4719-001997-dlp-chip.htm
I still love my DLP and I'm tempted to get a bigger one when they get even cheaper.