I have found fragments. I've sent 'em through the grinder too. Probably could have been avoided by more careful trimming, I will admit I don't like tossing meat that's "probably fine".
I switched to copper a few years ago (TSX). They kill fine if you hit them good, but I don't know if they kill as good when you hit them bad.
That study linked above is interesting, I think I've read that before too. I don't know how credible it is (I haven't looked into it) but if true it seems less than ideal. I'm not worked up about it and I'm not gonna try to convince anyone else to go lead free, but it's working for me for what I hunt. I mostly only shoot bears with a rifle though.