I have the K-5, K-5 IIs, K-S2, and KP as well as the K-20D in superb condition. The K-20D is a fine camera, but the others represent some real advancements in useful, practical terms, such as a better VF and better high-ISO, low-noise performance while preserving sharpness and detail. The K-5 IIs I highly recommend over the K-5, for its better AF, and no AA filter for better imaging detail compared to the K-5.
The K-S2 is a marvelously compact, lightweight design, having no AA filter but with a switchable filter if needed. Not a metal body or having a full array of on-body controls like the K-5 series, but with a very good build quality having WR and 2-dial operation as you are used to. Its control menus are easy to access. To achieve its compactness, it is minus the top LCD screen. But it has a very useful tilt and swivel back LCD screen, wifi, and a top button arrangement for shutter release while pointing the camera at yourself. With a WA lens, selfies even including a friend, are facilitated. Imaging quality is exceptional, its jpeg engine is great. Metering and flash metering are truly outstanding- I think more accurate yet than the K-5 series. It is not 14-bit RAW capable, but neither do I think is the K-20D, and you can't develop a RAW file in-camera as a TIFF image as you could with the K-5, if that is important to you. I don't know what lenses you have, but I saw yesterday that B&H still has a K-S2 left with the wonderful DA 18-135mm DC WR lens at a price saving nearly $200 off the lens if bought separately. With all of what is offered it is indeed a bargain.
In either case, I recommend adding "F" for "Fine sharpening" in the Custom Image menu. In "Bright" mode, the default is up +1 for sharpening, and I boost it up one more notch with both these camera models.
Last edited by mikesbike; 10-06-2017 at 12:35 PM.