The current Pentax DSLR models, like the K-5 IIs and K-3, do not employ an AA filter, the lack of which revealed better fine image detail in images with my K-5 IIs compared wth my original K-5. I also bought a KS-2, which is also minus this filter. It is my extra-lightweight model, and designed much like the heavier K-70. Last year I acquired the KP. Since you are happy to shoot jpegs strait from the camera, I can report that the KP does an outstanding job. Just remember to set up "Fine Sharpening" in the Custom Image menus. It also has a more advanced AF system, a more advanced SR system than any Pentax model so far, and a better set of controls than the K-70, as well as superior pro-grade build quality and durability. It offers outstanding low-light/higher ISO performance. it is a slimmer (shallower) design like the old manual 35mm film bodies. There is also the optional battery grip having much longer battery life, vertical shooting controls, and a larger gripable surface if needed, bringing the weight close to a K-3 II without a grip.
Since you are going for an upgrade, it is a worthwhile consideration. The lenses you use are of course also a factor in the quality you will get.
Last edited by mikesbike; 10-18-2018 at 03:32 AM.