depusm12, I have a 21SF but don't carry it IWB, in fact since I got my 30S last year I don't think I've carried the 21 at all. It's become a safe and range queen.
However, on one of my recent range trips the gentleman in the spot next to me was shooting his 21SF from a Crossbreed Supertuck. He was about my size, 6'2", 240 lbs, and he was wearing a pair of jeans with a polo shirt pulled out. I was suprised at how well the whole rig disappeared on him. He was practicing drawing from concealed cover while we were shooting. It seemed to work real well for him, and he was an excellent shot.
Sorry I don't have any pictures but this guy spoke very highly of the Crossbreed.