I've had a k-30 for a few weeks and a K-r for just over a year.
With the K-r the AF was quite off such that I had to set the fine adjustment between -8 and -10 (that is all the way to the limit).
With the K-30 it is absolutely spot on, and that with all the autofocus lenses I have tried it with:
- Tamron 18-250
- Sigma 150-500
- Tamron 10-24
- Tamron 90mm Macro
- Pentax 18-135 WR
It is also spot on when doing AF confirm with manual lenses, of which I have tried some old film camera lenses - a Cosina 50mm F1.8, a Tokina 28mm F2.8 and a Vivitar Series-1 70-210. It even worked fine with an 800mm F8 Samyang mirror lens .
It also seems not to have a problem focusing in tungsten light though I haven't checked that out thoroughly - just a few handheld photos, one of them attached.
This one is ashot of the Windows security sticker on my PC, it is a 100% crop. It was shot from about 6 metres distance with a Sigma 150-500 at 500mm and full aperture. No corrections are applied to the autofocus and the light is a tungsten spotlamp. No post processing is applied apart from the cropping. It is handheld by the way, which also tells you something about the in-body stabiliser.