I have a complete Ultegra 6700 group from a 54cm 2013 Specialized Roubaix. The group has about 1500 miles on it, but the shifters are about a month old were a brand new warranty replacement from Shimano. There are minor scratches on the rear derailleur, but mechanically everything is in great shape. The crank is an FSA Gossamer whose arms were painted flat black to match the matte carbon finish my frame. I don't have the original Ultegra crank, but the FSA is stiff and light. It weighs only 790 grams which is right on par with the Ultegra crank.
This has been a fantastic group that I've been totally happy with. Reliable butter smooth shifting every time! Parting out the bike to fund another build.
50/36 crankset, 172.5mm crank arms
English threaded bottom bracket
Braze-on front derailleur
Short cage rear derailleur
12-25 cassette (I also have a 12-23 6700 cassette or a 12-27 SRAM Force cassette if you'd rather have one of those)
KMC X10.93 10 speed chain
Brakes have been upgraded with Swiss Stop's superb "green" compound -- outstanding stopping power
Price: $475 shipped