By no means arguing that the Rohloff isn't worth the price, I'm quite sure it is, I just don't have the wherewithal at the moment
The efficiency of several of these hubs has been quite thoroughly tested - see
here. The SRAM T-3 was the best in this test; however, the example they used had been relubricated with light oil instead of the usual grease. A similarly treated Sturmey AW was right on its heels. The Rohloff was generally superior to the Shimano and Sturmey 7-speeds. Now, I know that the AW has had trouble with jumping out of gear under strain ... I wish I knew whether the SRAM had similar issues. I also wish I could remember where it was that I heard about a fix for that problem.
By the way Dave that tandem you showed at NAHBS was completely mind-bending. Nicely done.