DxOMark report on the K-5II.

"The Pentax K-5 II is a remarkable piece of kit, it scores better in the DxO mark tests than several very highly thought of, full frame DSLRs, beating all the cameras made by Canon! It manages to do this in a body that is very reasonably priced. Add to this that you can fit lenses to the K-5 II that Pentax made as far back as 1975 and the multitude of independent lenses that are available and this camera becomes not only a remarkable performer but also a fantastically versatile camera at an exceptional price."

link

The only thing I can find wrong with that report is that lenses much older than 1975 vintage can be used with the Pentax camera system. With the help of the M42-K mount adapter, lenses from the 1950's can be used very effectively.

It's a good (and glowing) report.

It sits between to supposed heavyweights. Good score, can't wait to see where the IIs sits

hmm interesting that they find the sensor performs better than the mki and that the buffer holds more, looks like there are more improvements than Pentax let on...

It could juts be sample to sample variation, but although it’s hard to pin down (and it could just be wishful thinking) my K-5IIs seems to perform better than my old early model K-5. Apart from the as advertised improved low light AF the images do appear less noisy at high ISO than the K-5.

http://www.imaging-resource.com/IMCOMP/COMPS01.HTM

No difference according to the above comparison

I tend to agree.

K5 vs. K5IIs - different story. IIs is definitely better.

The K-5 I and K-5 II also both score 82 at DXO and the sensor measurements show a very slight decrease in performance at higher ISOs for the MkII versus the MkI. No data for the K-5IIs yet though

There is bound to be some variation is noise from sensor to sensor even between sensors on the same wafer, and bigger variation between processing batches so a small change is not going to indicate anything significant.
Also as with all semiconductors noise is very temperature dependent, getting worse at higher temperatures, so a change in ambient temperature or the possibility the camera was in ‘Live View’ just before the measurements were made will change the noise levels. It would be interesting if they published the camera temperature – which is available from the EIF information.

Write up says low light improvements, doesn't say in AF!

Yeah there's nothing in those measurements to worry about. negligible difference