I have had my K-3 since April and have been an active member on this site since 2007. My opinions and observations are:
- The K-3 has two reported issues (runaway mirror and random system lockup)
- Both are relatively rare with random system lockup being the more prevalent
- The incidence of problems with the K-3 is low and similar to the other top models that preceded it with the exception of the original K-5 which had numerous troublesome issues that were present in fairly high frequency. I can confidently state that the K-3 is the best-made Pentax dSLR to date and possibly the best AF camera in the history of the brand.*
- Industry-wide, the incidence of serious defect for dSLR cameras is about 4%
- My general advice to all who are purchasing an expensive digital camera (regardless of brand) is to buy an extended warranty if one is available. Pentax sells a 2 year extension for $20 USD.
- Any of the cameras on your short list will be a capable tool
My problems with the K-3 make a short list:
- Random and rare system lockup, usually while using the playback mode
This has happened about a half dozen times since April and not once in the last two months.
Happy owner? Absolutely!
Steve
* Comparison to the build quality of the mechanical models is sort of silly. It is unlikely that my K-3 will still be operational 50 years from now in the same manner as my Pentax SV.