Chris T Loc: from England across the pond to New England

Don't know, really, Nosaj ... I've not taken the plunge, but REHess was considering one. Why not send him a note?

The big differences - apart from the amazingly high ISO (819,200 as compared to 102,400 of the K-70, and 51,200 of the others) is the focal points (27 - same as K-3 / K-3 II) and 11 on all the other APS-C bodies, the LACK of phase detection, and the use of a tilting screen (as opposed to the Fully Articulating variety of the K-S2 and K-70) a 7fps shooting speed (compared to 6fps of the K-50 and K-70) and the full 5" wide size of the body (plus additional weight) over the K-50 and K-70.

Here's the Camera Decision Comparison - as noted before - with the K-30, now replaced by the KP.

https://cameradecision.com/multi-compare/Pentax-K-50-vs-Pentax-K-S1-vs-Pentax-K-S2-vs-Pentax-K-70-vs-Pentax-KP

Chris T Loc: from England across the pond to New England

One more Pentax Camera Comparison page - in this one, you can see the K-50 has been removed in favor of the K-3 (disc.)

https://cameradecision.com/multi-compare/Pentax-K-S1-vs-Pentax-K-S2-vs-Pentax-K-70-vs-Pentax-KP-vs-Pentax-K-3

Chris T Loc: from England across the pond to New England

Last one - this is just a comparison of the top tier of Pentax models - K-1, K-1 II, K-3, K-3 II and the more recently-released KP.

https://cameradecision.com/multi-compare/Pentax-K-1-Mark-II-vs-Pentax-K-1-vs-Pentax-K-3-II-vs-Pentax-K-3-vs-Pentax-KP

Chris T Loc: from England across the pond to New England

Nosaj - just found this -

Pros
24-megapixel APS-C image sensor. 5-axis image stabilization. 27-point focus system. 7fps continuous shooting. Pentaprism viewfinder. Tilting LCD. Weather-sealed design. Modular grip system.
Cons
Dated video features. Single card slot. Short battery life. Very small Raw buffer. So-so tracking capability. Slow, buggy Wi-Fi app.
Bottom Line
The Pentax KP features a svelte design, protection from weather, and excellent imaging, but is held back by Wi-Fi issues and so-so video.
When the Pentax KP ($1,099.95, body only) was announced earlier this year, I looked at its price and specifications and pegged it as a dramatically redesigned upgrade to the K-3 II. After shooting with the camera over the past couple of months, I realize I was incorrect. The KP includes some compelling features, including high-resolution pixel shift capture, and is sized perfectly for use with the compact Limited lens series. But it's not as strong an option for capturing fast action as the K-3 II, and its video functionality is way behind the times. Dedicated Pentax users who love the compact prime lenses available for the system should think about the KP, but there are better options out there if you fall outside that niche.
The KP is slimmer than previous Pentax SLRs, measuring 4.0 by 5.2 by 3.0 inches (HWD) and tipping the scales at 1.5 pounds without a lens. The dimensions don't do the compact size of the body justice, as the maximum depth is determined by the protruding lens mount. Pentax offers the camera in silver or black.
Three handgrips are included, varying in depth. I liked using the deepest, as I was using the body with a zoom lens for most of my photography. But if you stick to small, pancake primes you may prefer one of the shallower options. You'll need an Allen wrench to change out the grips; you don't get one with the KP, but if you've ever bought Ikea furniture you'll have one somewhere.
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From PC Magazine