I've seen video's of the shifting Pentax sensor, and it was a lot more movement than i ever imagined.
One of the most under-mentioned advantages of Pentax K5 and i think K7, is the auto horizon leveling ability of the camera. I noticed soon after getting my K5, that i was doing a lot less PP correction of the horizon and thought that was odd. Then it occurred to me that i had turned on horizon leveling when i got the camera. It actually works quite well. You can turn off SR and still have auto horizon on, or you can turn both off. At some angles of tilt, the programming must say, this guy really wants things tilted so we aren't going to try anymore
Yes, inbody SR really has its uses!!!