The ability to shift while standing still or climbing is a definite plus. I also like the fact that everything is sealed up and I don't have to worry about cleaning or adjusting derailleurs.
I think I'm going to go with the frame only. If I don't get a Rohloff I'd prefer an SRAM drivetrain and v-brakes over the Shimano and discs of the complete.
From what I've read an 18" sounds like the right size for me at 5'10".
I am 5' 11" and went with the 20" frame Big Dummy based primarily on top tube length compared to my other bikes with flat bars. I probably could have also fit an 18" pretty well but I was influenced by the fact that the worst fitting bike I ever had was a too small frame bike sold to me by an LBS when I first started riding again. IMO a case of their selling the size they had in stock rather than fitting it to me but I was too ignorant at the time to know what I needed.
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Gear Hubs Owned: Rohloff disc brake, SRAM iM9 disc brake, SRAM P5 freewheel, Sachs Torpedo 3 speed freewheel, NuVinci CVT, Shimano Alfine SG S-501, Sturmey Archer S5-2 Alloy. Other: 83 Colnago Super Record, Univega Via De Oro
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http://groups.yahoo.com/group/Geared_hub_bikes/