I must admit that while I like the idea of a greater than 100% dura = +X, i'm not stuck on it. Personally, I would just like to see more DEPTH to the repair system. That could take on any number of forms. I think there is a lot of opportunity there to increase the playability, viability, and importance of crafters without forcing a negative aspect on the players who do not like crafting.

Perhaps a better example would be a "Battlefield Kit" where in a crafter can provide temporary boosts to weapons/armors, etc., mid battle. While that would not necessarily be viable with the current battles in the game, it would be viable should they ever add longer battles (I'm thinking Kirin, here). Something that encourages crafters to support combat in some way without actively being in the combat would be a level of depth that IMO is ideal.