I ran 105 (5610) and r540 pedals at the same time on different bikes. In my experience the only thing close was the price. The 105's were clearly better - a touch wider and no plastic center piece. I have 6620 Ultegra's as well and can't really tell a difference over the 105's.
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"The older you do get, the more rules they're gonna try to get you to follow. You just gotta keep livin', man, L-I-V-I-N." - Wooderson
'14 carbon Synapse - '12 CAAD 10 5 - '99 Gary Fisher Big Sur
Last edited by dtrain; 01-08-13 at 01:25 PM.