I really like the idea but on my hub geared bike I just cover the chain in some old gear box oil and wipe it occasionally. I reckon to spend no more than five minutes a week doing that on a bike used all winter for an off road commute. The current chain is 2 1/2 years old. So from a maintenance point of view the time savings are pretty small.
The lower weight is a good thing but the bike I have with a hub gear is heavy all round and therefore the weight saving to go to a belt drive would be insignificant and the cost very high to modify the frame and the hub.In the summer I ride a bike with a 1×9 setup which is light enough and as it’s only a nice weather bike again doesn’t need a lot of looking after.
So I think where it would really score is if you want a light as possible single speed or hub geared bike for all year round use.
Which is exactly what I would want if I could only have one bike.