Not long bought our Cannondale Road 3 tandem, which we're really pleased with. But as per usual, can't resist changing bits, mainly to save weight. I'm thinking of ditching the Avid mechanical discs what were fitted originally and using Shimano XTR v-brakes. Just wondered if this is a big mistake and we'd struggle to stop on steep descents? Our combined weight is a little less than 300lbs. Your thoughts are most welcome.