re belt drive on Rohloff: For the last few years Rohloff have been fitting their new style driver which makes life easier for the average user; it allows easy replacement of the chain drive sprocket which is now fitted with a spline. This replaces a unique (multi-start) screw thread arrangement for the sprocket. It turns out that the splined arrangement doesn't like a lot of preload on the chain/belt; the sprocket starts to orbit around on the driver, at first by a small amount (determined by the clearance between the parts) and as time goes on by an increasing amount and making a lot of noise too. (BTW the same thing often happens with belt drive sprockets fitted to other IGHs with the conventional three-lug fitment.) Problems are pretty much guaranteed with belt drive because belt drive requires a fair amount of preload.
This has caused plenty of grief to owners and was soon a known problem but it didn't stop folk being sold expensive machines which were bound to give trouble:https://www.cyclechat.net/threads/cycling-around-the-world-sadly-had-to-return-for-major-repairs.227214/
I'm sure that belt drive suits some folk but I would not choose one myself; chains and sprockets are readily available, cheap, and don't fail often and/or without due warning. If they do fail they are easy to repair.
One of the reasons for buying a rohloff is that it is an efficient transmission. However if you fit a belt drive to one, you have thrown this advantage (and plenty more besides) away.
[Belt manufacturers will produce data which suggests that their belts are efficient. However this data is generated under constant torque conditions, may or may not include a representative preload, and isn't representative of what happens when you ride a bike; the torque varies wildly during pedalling and each time it does the belt stretches slightly and then relaxes again, in a way that doesn't conserve energy. Motorcycles are also available with a choice of belt or chain drive and they too are similarly somewhat 'pulsey'; dynamometer tests suggest that you could be losing tens of percent with a belt drive. ]
To anyone that doesn't care about efficiency, and has never seen one break and/or had to deal with the consequences, belt drives may seem like a really good idea. However if you have seen a belt drive fail or give trouble for some stupid reason that you wouldn't expect, you might think otherwise.