I have a couple of dive buddies that are tech divers and they are trying to get me to head in the direction of diving doubles, But I gotta tell you, just watching those guys lug their double steels around makes my back hurt. I do like the idea of redundant first stages, and I also like the idea of only having to carry one tank at a time. I'm wondering if there's anybody in southeast Michigan that teaches side-mount (hence the name of the thread).