Stability is absolutely fine, I carry my camera on an R-strap (
BlackRapid: RS-4 Strap ) which allows it to sit neatly at the hip but pulls up very quickly into position to shoot.
I have smallish hands and also suffer arthritis which means that anything with too much weight becomes painful quickly, however I am able to hold the K-7 very easily.
I have generally shot with pentax SLR and DSLR, however diverted to the Sony alpha-100 in 2006 following an episode where I got to play with a Canon with image stabilized lens. At that time Pentax were talking about in body stabilization but it was still unclear when they would release such a beast. I loved the in body stabilization of the Sony.
I returned to Pentax a year later as a result of killing the Sony on a glacier in New Zealand (I took a fairly bad fall in which I was largely unhurt other than pride, however the Sony died). Pentax had by that time released the K10 and I succumbed to pressure form my hubby to return to Pentax but always felt that the stabilization was not quite as good. Well the point of this ramble is, NOW the stabilization is as effective as I could wish it to be. I am more than happy with how this camera performs.
As for the model in the last shot, well he was happily absorbed in playing his nintendo DS and was oblivious to the photo being taken.