I've used them for 2 tours on my Rohloff touring bike. The first time I hardly used them because when you have your hands in the drops, they're too far from the brake levers and that made me uncomfortable. The next tour I mounted some road brake levers to them (needed a shim b/c the bar diameter is still mtb width), sort of making my own drop bars. It worked, however it's not ideal. It's uncomfortable to rest your hands where the bar ends clamp on the flat bar. I guess you can put lots of padding there and make it work, but I would just skip that spot and my hands would hop from the tops to the sides. Secondly when you have your hands in the drops, you'll need to bend your elbows a bit so the clamp doesn't hit your forearm. That's not a big problem tho.
Overall it works and it's the best method i've found yet. I've tried this shifter: http://www.mittelmeyer.de/html/rennlenker.htm
It's neat how the brake cable can pass thru the shifter, but it has no bearings like the standard Rohloff shifter and it was too hard to twist, about the same effort of the sram rear derailleur twist shifter, and on a long ride my carpel tunnel would feel strained.
The big problem with mounting drop bars in my case would be the hydraulic disc brakes. No one yet makes road levers for hydraulic disc brakes that I am aware of. I suppose that I could switch to Aztec BB7 road cable operated disc calipers and drop levers but I also like the flat bar for in town use. Looking for varied hand positions capability.
The bike is a Civia Hyland Rohloff. The frame geometry is basically sports touring according to the info given in Berto's Upgrading Your Bike book. A fun ride which I am just trying to increase the versatility of.
I have other bikes including an approximately 83 Colnago Super Record judging from crankset date. Also in the process of doing a drop bar gear hub bike with the SRAM P5 5 speed gear hub too. That one currently is set up with an older Sachs 3 speed hub.