Originally posted by SSGGeezer If weather resistance is an issue or might become one in the future, go for the K-70 for the weather sealing.
K-S2 is weather-sealed too. (You might be thinking of the K-S1, which isn't.)
Lea there are quite a few threads on Pentax Forums comparing the K-S2 and the K-70. For example:
Should I buy a second K-S2 or a K-70 - PentaxForums.com K-S2 vs K-70 - $100 difference or a lot more? - PentaxForums.com Buying advice - K-S2 (or wait for K-70) for K-5 user - PentaxForums.com
And here's a comprehensive comparison of the differences between the K-S2 and the K-70:
Comparison: Pentax K-70 vs Pentax K-S2 - Which one to get
Most of the basics are the same. Same battery, same metering, same autofocus through the viewfinder, two control wheels, flippy screen (great feature), no AA-filter on either (makes a noticeable difference in detail). Some of the notable differences are that the K-70 has a 24mp sensor (v 20mp), 14-bit RAW (v 12-bit), pixel shift, better AF in live view, continuous AF in video, and better image stabilization.
How much these differences matter to you is something you will have to decide. If the difference is only $100, as suggested above, the K-70 looks like better value. But the K-S2 is still a very good camera, and would be a big upgrade from the K-r.
However the other thing that the specs don't show is the feel of the cameras. I have a K-S2 and I don't find it as comfortable to hold as either the K-30 or the K-3. But then my partner prefers it to either of those - many other women might find the same. The feel of the K-S2 might also be more like the feel of the K-r (I don't know, the K-r looks a similar size). If you can get your hands on them, it will help you decide. There might be some forum members in your area who would be happy to let you try their camera.
One other small thing. K-S2 comes in white and some other colours, K-70 is black (or silver?) only. I have a white K-S2 and I've come to like it. People don't find it as intimidating.