The Rohloff gives a larger range of use since it offers 14 non duplicated speeds instead of the previous 7 (equivalent of 3x9). This allows steeper climbs and faster descents. Before the rolhoff, i could not accelerate while pedalling in descents, now i can, up to 80 km/h...and confortably overtake trucks.
I chose the Rolhoff over other hubbs because of its quality, wanted the best for the demanding lady. It equips mainy downhill mountain bikes.. After several deraillers broken on stones, i was convinced the internal hubb would be a safer option. Another side advantage of the rolhoff is that you need shorter spokes, which makes them more unlikely to get broken from terrain repetitive shocks. And last but not least, you can shift speeds without moving, which is important if you dont want to damage the internal hubb (start on easy ratios). No need to lift the rear wheel if you got stuck downhill to prepare to climb the next hill...stop, ease, and slowly but surely start climbing. I noticed i used less energy with the rolhoff, since the gear was almost always appropriate enough to efficiently use muscle propulsion.
The problem for the moment is to allign perfectly the human propulsion chain, since the rolhoff is narrower than the 7 speed system derailer, the chain guide had to be removed to install the hubb. I left the bike to the local mountain bike workshop in hope he ll find a solution for a totally stable propulsion system. We also had to remove the kick stand installed on the rear wheel, no room left.
Regarding durability, i didnt ride enough yet to give a reliable feedback. Rolhoff warranties the hubb for two years, and when i asked about warranty problems to the mecanic due to the 3000W engine power, he simply answered : "no need to specify it".
The creator of the spider mid drive bike also installed a rolhoff, he mightbe able to give you a better feedback about its durability....