I ride a 40 mile shop ride every Saturday with a fast group. My experience:
-2011 Specialized Tarmac with full Dura Ace: My fastest option.
-1984 Raleigh Competition modernized with same full Dura Ace: Sometimes able to average what I do on the Tarmac but takes noticeably more effort to hang on during an acceleration.
-1985 Schwinn Tempo friction 6 speed: I get dropped any time I've tried it; always during the accelerations. Something to be said for more gears and brifters.