I've got a K-3, K-5 and K-30 - and K-30 is often my walkabout body because it is noticeable smaller and lighter than the other two, and it takes AA's which it occasionally handy when I'm somewhere where I might not be able to charge the standard battery (or I leave the charger behind - which I did when we went to Thailand
). The only things I miss from time to time are the larger buffers and higher frame rates of the other two bodies, and occasionally the top screen because that allows me to check the basic exposure settings without delving into the rear screen menus before I start shooting.
I've got biggish hands and the K-S2 body is too small for me, and I never felt the need to "upgrade" to it, but the tilting screen looks to handy at times (I rarely if ever use live view because of poor eyesight "accommodation" issues due to my age, and reflections issues - but I appreciate that 90% of camera/camera-phone users now do!).
Therefore I would hope that the K-70, or whatever it may be called, is not (much?) smaller than the K-30/K-50, and has some of those "missing features" (although I don't hold out any hope for a top screen). FWIW, I was looking to buy something the size of the K-S2, I'd be looking more in the micro four-thirds direction, but I'm not so happy with 4:3 aspect ratio as the 3:2 of the Pentaxes,