I actually give IDPA credit for keeping their weight limit, whereas other disciplines have continued to increase their weight limit as manufactures push the envelope. As it stands, at least 3 manufactures that I can think of (Walther, Sig, and CZ) have guns in their lineup which are made to make weight in IDPA. The weight limit for SSP and ESP is roughly what a stock 1911 weighs, so that seems reasonable to me.
Personally, I don't think the gun matters that much in IDPA. As long as you can shoot zeroes with your gun, your split times don't factor in that much. My IDPA guns don't come close to the weight limits, but I've never felt that I was at a disadvantage to the guys with maxxed out x5 legions.