I like your setup - creative! I agree with bbqking on the smaller pieces of meat. The bigger the pieces, the more susceptible they'll be to gravity pulling them down and spinning on the skewers. However, we do a lot of kabobs, and when I have larger pieces, I try to cut them into rectangular boxes and skewer them along the pieces' length so there's more weight distributed along the skewer center than away from it. Probably not a perfect solution, but it works for me. I'll have to give this setup a go next time!