I have been using my K20 for almost 3 years. During this time, I have been saving here and there for a replacement - just in case. The K20 has been doing wonderfully. I had considered the K5, and literally decided to bypass it and wait for the end of the next product cycle, before making a decision. I found with the K20 that if you acquire at the end of the model run, you can get a great camera at a great price.
I was able to pick up the K20 new at the very end of the model run as the K7 was announced for $650. I remember watching the K7 end its model run with a new price of around $750. So, I was estimating that the low for a new K5 maybe around $800 to $850.
In mid January, I happened to check my email before going off for the day and just happened to check the forum here and saw a post about K5 excellent pricing. Clicked on the link and saw that Samy's camera over in LA (an authorized Pentax dealer), was selling them for $750. I just picked up the phone and ordered - since I had already saved the cash. Now some have speculated that it was a pricing error. I asked when I called back to check on shipping and they would not say one way or another. I'll chalk it up to pure luck, timing and good fortune.
The only reason I was even considering the upgrade was that the K5 provided improved image quality & dynamic range in ambient low light / shadow conditions. I shoot almost exclusively in the evening and nights. So, there was definitely a reason to consider an upgrade.
Now the K20 is really an excellent camera - hopefully the K5 will perform just as well. I have a few weeks left on my 2 year extended warranty free cleaning and check out. I'll take it over to CRIS get it tuned up and then consider what I am going to do. It has been a really good and dependable friend - teaching me a lot.