I inherited a "junk box" from a DH buddy, including some old-looking 6" aluminum rotors ( I know they're alu cause of the weight) - my question is: considering I've got avid mechanicals (that I've played around with, and can adjust to fit the uber-thickness of the rotor), would I need different pads to use these rotors? I like the idea of aluminum rotors for my xc bike because they're lighter than the stock avid rotors, but have never really heard of people running aluminum rotors. Anybody have any insight?