That's the route I'm personally going for, all large PVP / faction battles (on our server at least) are fought with players with full diamond enchanted gear... and not so much with bending. I would rather see it the other way around, the heavy armor should inhibit bending imo. Your tradeoff for using such heavy armor is taking a hit in bending ability damage/ increased cooldowns or something.
The exception of course should be metal benders using iron armor, as this naturally augments their bending. Any other user wearing iron, gold or diamond should be penalized.