I've tried an off hand draw and failed miserably. I have bad shoulders, shorter arms than torso, and a bit of a paunch. A perfect trifecta of evil. I think this type of draw is where cross-draw and up-side-down shoulder holsters come into their own. Even SOB makes this manuever much easier. However, because of my evil trifecta I carry a snub in my offside pocket. Solves that problem quite nicely.
edited to add: Just thought that those who like to go behind the back to draw may wish to play around with a backward cant. This would allow the grips to be more accessible for weak hand. Also when clearing a cover garment you don't have to stop the backward sweeping motion to reverse and catch your gun on the forward movement. It would provide an all over smoother draw stroke. I'm gonna try this out tonight for Sh*ts and Giggles.