My experience so far hasn't been good. I sent in my DA* 16-50 f/2.8 lens because of focusing issues on the K-7 (FF even at -10 correction). The lens they sent back also had this issue, but also had an additional problem with the focusing mechanism (video of problem here:
YouTube - Another bad 16-50...) so it immediately went right back to Pentax. This time around though, it went to the CRIS facility instead of Pentax, so I'm even more concerned.
Not only that, but my K-7 is at the facility too; it won't power on anymore. So I'm 0 for 1 so far, with 2 more chances. I'll let you know when they (eventually) return...
- Jason