I finally got around to playing with the ISO 6400 RAW sample of the cat in RawTherapee & compared the RawTherapee jpeg to the OOC jpeg from the camera. Pentax has really revamped their jpeg engine! There's really not much more fine detail to extract out of the high ISO RAW file than what's coming out of the OOC jpeg.The K-70's jpeg engine is actually quite impressive! All previous APS-C Pentax jpeg engines suck when it comes to anything past ISO 800.
Like when I compare a higher ISO OOC jpeg to a RawTherapee jpeg from my K-50, you can tell that there is a big difference between the camera's jpeg engine & what you get out of the RAW file.
It looks like Pentax has closed the gap on that difference with the K-70. Software makers will need to develop RAW editing software that can pull out far more detail. The future looks bright!
Now the only question remains is this: does the K-70 use the same aperture block that's in the K-30/50/S1/S2? Hmmmm........