When I bought an e-bike for my commute I decided to splurge on one with a belt and I regret nothing. You spend less time messing with it and the bike is a lot nicer to work on when you don't have to worry about getting grease all over your hands. If I was to buy a regular bike I'd see if something with a belt was available within my price range because I like it that much better.
Mind you, I had that bike for less than two years at this point. I don't know how a belt behaves in the long run.
My current bike has no motor and uses a Gates CDX belt drive with a Shimano 8-gears internal gear hub
I believe thats enough, more gears are not needed
my older chain bike had a motor and I could just let the motor do the work if my chain got too rusty/dirty which resulted in higher wear (loose chain)
As someone who does not have a belt drive, one of the biggest promotions of them I see is a belt doesn't stretch, which is true, they just snap. And I could be wrong, but with how they are less maintenance, I don't see how it isn't longer repair times when things do break.
Sometimes chains snap too. But that is an easy to fix it in a pinch if you aren't in the middle of nowhere. I just walked my bike to the nearest store with basic bike tools (walmart), bought a chain break tool, and used some quick links I had in my bike bag to repair it and get back home. Not sure how easy doing similar repairs would be to do without keeping a spare belt on you.
I have an acoustic bicycle with Gates CDX and Alfine 11 IGH. The use cases for this combo are not for me. The absolute win is the lack of maintenance and no greasy chain. However chain maintenance is a non-issue for me. A little care goes a long way. And I'm familiar enough with bikes to avoid the "chain print."
My issue with Gates drive is that the drag is very noticeable. A properly tensioned belt introduces a lot of drag. Adding in the drag from the IGH seals, I always feel like a brake is dragging. Another concern for Shimano IGHs is that they can leak when the bike is on its side. This is a non-issue for bicycles in use, but my bike is designed to be packed for airline flight. It's almost guaranteed that the hub will be vertical during transport, and I've had to clean up small oil spills after traveling with my bike.
Changing gear range is expensive and always requires a student/new belt. On a chain drive bike, changing gear range is simple and relatively cheap. So if you're going the Gates route, try to have a good understanding of your desired gear range before taking delivery.
Finally, repairing a flat tire on the rear is a way more involved process. If you are very familiar with working on belt/IGH bicycles, it's less of a concern. But changing a tube on the side of the road in the rain in the middle of the night (because OF COURSE that's when flats tend to happen) is a real pain. The change goes from a two-minute operation with a chain drive to about 12 minutes (for me) with the belt. There are ways to mitigate and reduce flats (Schwalbe Marathon tires, tubeless tires, tire strips...), but these all introduce some other factor(sl that either increase maintenance, require more tools/supplies, or increase rolling resistance.
Are Gates drive bad? No. They carry a lot of benefits for urban commuters. People who don't work on their own bicycles are an excellent target audience. The system just isn't for me.