One Rohloff failure that seems to occur from time to time is spokes pulling away part of the flange.
If that happens, you either wait for a replacement Rohloff or use whatever you can find locally instead - this would probably be a derailleur wheel so you would also need a hanger, shift lever, new chain and rear derailleur. And you would have a limited range of gears with the single chainwheel.
Much simpler if the same thing happens on a derailleur bike, you just swap out the rear hub and rebuild the wheel, if you are lucky you can even use the same spokes. Or swap out the entire wheel. This happened to me on a tour to France with a derailleur bike (before I moved there). I cracked the flange after crashing the bike on ice in the pine forests south of Royan, but I was lucky, the wheel held up for several hundred kilometres and finally broke as I arrived in the road where I lived. I just had to push the bike for a few minutes.
On the other hand, with my present combination of Rohloff with Chainglider, I avoid a lot of the disadvantages of derailleurs, the list is quite long, so just a few here:
- fast chain wear in wet/mucky conditions,
- rear derailleur either wearing out or picking up road debris (had both cases), then jamming in the spokes,
- chain coming off the inner ring and getting stuck between chainring and bottom bracket shell, damaging the latter.
So I reckon far fewer problems with a Rohloff as compared to a derailleur, but something does go wrong you may well be stuck for longer. And if the bike is stolen it will (probably) cost more to replace.
Now that I have a Rohloff bike, it is my first choice for heavy touring in hilly areas, my second choice for that use would be a 3x7 or 3x8 wide-range derailleur system. I'd consider taking my old 5-speed hub geared bike for a long tour on mainly level ground (Loire-Danube cycle route or the part of the North Sea cycleroute between northern France and Denmark) as it has been very reliable and isn't worth much if it gets stolen.
It may be heresy here on the Thorn cycling forum, but you don't absolutely need a Thorn bike for a mega-tour. For my 3,300 km Brittany-Spain-Brittany trip in 2011 I converted my old steel mountain bike to drop bars and used that. The frame weighed about the same as a Thorn Nomad, but probably more comparable to the Thorn Raven in stiffness. Not so nice as my current Thorn Raven Tour, but it did the job.