I've got both the K-70 and the KP.
The KP has a few "advantages" … an extra three stops of low light sensitivity, a 1/24000 sec. shutter speed (with limitations) and the a/f system can be better with a long lens on a moving subject.
-3EV to 20EV Vs 0EV to 22EV, I'm not sure what this does, the important auto focus sensitivity is the same across all 3 current cameras K-1, KP and K-70 having -3EV to 18EV.
I was photographing my K-30 yesterday (to sell it) with my K-70 and I'm still impressed the AF worked in such low light on a black body. It wouldn't have worked in reverse. The -3EV AF is brilliant.
You forgot 7FPS vs 6FPS
The fully-articulated screen on the K-70 has distinct advantages when shooting at some awkward angles.
This swung the vote for me and the K-70 has a proper hand grip, it is great for single handed shooting which I also needed to do yesterday... product photography for eBay, hold stuff in one hand and camera in the other.
IMHO, unless you need the "plus points" of the KP, the K-70 will likely give you all you need.
I would still make the same choice again, I'm intending to use only K-70 for the next 10 years, not joking either and may have learnt how to use all of it by then LoL
Both cameras are extensively configurable and capable, and will require quite some time dedicated to trawling through the handbook discovering all these capabilities and learning how to best take advantage of them!
You can't eat an elephant all in one go, it will always be complex, I try to use it as simply as possible on manual like a film camera with extras like the timelapse modes which are great. Star streaming anybody? Again I think only Pentax does this and you can load it straight onto YouTube without any post processing.
Also, don't ignore the "Digital Camera Utility" software supplied on CD. A bit quirky, again with a learning curve, but extremely capable … and free
Never opened it, Lightroom all the way and Nik Collection.