I’m currently looking for an ebike & was really drawn to the hub geared bikes, something like the Kalkhoff Inergrale with an 8 speed alfine hub & carbon drive belt. I can understand the problems with drive belt replacement, but are the hub geared bikes not up to the stresses put on them by the crank motors?
I have no actual data to draw from, but using one transmission path for both muscle and motor power has always struck me as being suspect, particularly with regard to accelerated wear and tear caused to chain and sprockets.
Plus, as someone recently pointed out on Pedelec (someone with a Bosch middle motor), when his goes wrong (its new and has gone wrong many times), he usually has to walk home, as he gets no motor power or pedal power getting to the rear wheel.
Which is why I personally prefer a hub motor, front or back wheel, and separate gear and chain drive or similar.
A rear hub motor probably precludes a hub gearbox though (Guessing only).
With regard to hub gears, apparently they do require far more maintenance (going from a recent topic here), which I find strange, as Sturmey archer gears that I had as a kid, just worked, with the addition of a few drops of oil, year in year out! It appears that we are going backwards in some areas.....
My preference, which brought no problems to do with either gears or motor, on 2 e-bikes, over now more than 8 years of e-bike riding, was Derailleur type gears from Shimano (both 21 gears), and a rear wheel hub motor.
Easy to clean and lubricate. I had to change the cassette on the first bike after 6 years of heavy usage! Under 20 UK Pounds.....Plus two chains, cheap on ebay.
I can see the point of having a front wheel motor instead, but only tried one once myself, as puncture repair is possibly to my mind, made easier.....guessing only.
But a front wheel motor would also make it easier for you to have hub gears at the back, if you are set on them!
Just a few thoughts!
regards and do have a great day
Andy