Our other major debate was Shimano XT groupo vs Rohloff Speedhub for the gear train. In one corner we had Keith (go with a derailleur!), Bryan in the other corner (the Rohloff is really nice, and virtually maintenance free!), and Peter somewhere in the middle. It wasn’t quite that black and white, with Keith enthusing over the engineering of the Rohloff, and Bryan pointing out that if something goes wrong with the Rohloff, it will likely be hard to fix.
I had been hoping to be able to see a Rohloff hub in action (and maybe even ride a bike with one), but even at BicycleMan they’re pretty rare. They’re much more common in Europe, but in North America everyone uses derailleurs instead of hub gears. Peter mentioned that some of that is related to different import duties for hub gears vs. derailleurs in Europe. In any case, the Rohloff is very expensive here (a 35% premium on an already expensive bike by my calculations), but it does provide a much better-encased shifting system, and has proven to be very reliable for many people on long tours. That said, the Shimano XT system is very good, and extremely refined. I expect if we go the XT route we’ll spend more time maintaining the geartrain, where the Rohloff is very low maintenance. However, if something does go wrong with the Rohloff, very little is user serviceable, and what we could service is very different from a normal geartrain. We’ll need to do some work learning to adjust the cables on the Rohloff before I’m comfortable, but I need to improve my bicycle maintenance skills in any case.
Another option is the SRAM Dual Drive 24-speed (this is the base configuration on the StreetMachine). For extremely long distance touring, I think this has the downsides of both a hub and derailleur. It is difficult to service and get parts for the hub, and the cassette and derailleur are exposed to mud and dirt, requiring more frequent cleaning and maintenance.