to be fair, using the fact the rim is weakened as a reason to do this isn't very good... after all, grinding doesn't take away much material, it only condition's the surface. I'd be lying if I said it didn't weaken the sidewalls but even after they've been weakened they still hold up to the forces trials put on them (in my experience).
As for saying the trials community is far behind everyone else, if it isn't broken, don't fix it!
We all love grinds, they work well and I've never had any problems with buckling/ the wheel going out of true because of one...
Also, when the brakes are applied it causes friction, Friction wears down surfaces.. I can't get round the fact these don't wear down, surely they will eventually wear down? giving you a smooth plastic braking surface? That's the bit which is putting me off...
Looks like an interesting alternative but it sounds a little too good to be true :/