Sounds like something you should win for, i mean, if you were tussling near a cliff and you threw them off, you'd definitely win.
I tend to think that the more i read this, the less tangible opposition to the idea there is, i realize the concept would suffer growing pains, we all remember some of the bizarre fights in the early ufc's, Gary Goodridge holding onto the cage and pawing his way to his corner sticks out in my head like a sore thumb, but i really think, if you had the concept totally open, and much like the early ufc, tried to get anyone who wanted to try it onto the platform, i think within a few years, you could have a completely legitimate sporting contest, that probably could rival the ufc, i do realize there is scope for injury with people being able to fall off, but is it really much worse then a bloke being pinned against a cage and battered from a mounted position?
I can't say i have, but to be fair, i only ever fought once outside of a boxing ring or wrestling (sambo) mat, that isn't to say that in certain places in the world, the idea of throwing someone so their fall is exacerbated by a feature of geography wouldn't be completely unheard of.