This entry made me think of the Ultimate Fighter episode when Rich Franklin was telling Matt Serra to go into the fight on his knees. I never really understood what he was going for, but after reading this post I can't help but wonder if that's what he meant.
I like the creativity of this setup: presenting the backdoor sweep, available for a shot, can't be kicked in the head (in MMA at least), it's a good perspective. The only thing I wonder about is: if the opponent is significantly taller, aren't you giving him a stronger base by allowing him to push with his legs whereas you can't ... while on your knees? It almost sounds like a move that you have to be prepared to immediately react to your opponent instead of offensively take action (i.e. - if he steps back shoot asap so you don't eat a punch, if he leans in sweep asap so he doesn't gain too much control for a takedown/pass).