Ultegra 6700 rear derailleur w/ 6600 shifters?
I'm building a commuter bike and have Ultegra 6600 shifters, front derailleur and crank. If I use a 6700 rear derailleur, is it going to reduce the drive train performance in any way compared to finding the matching 6600 rear derailleur?
Shimano puts a scary-sounding disclaimer on the 6700 spec that suggests you need to use other 6700 shifters and parts. Is that just marketing hype to get you to buy everything again, or is there anything to that?