Great advice !
It is wise to run the best you can, at all times.
Yes, I do have thoughts... (Possibly delusions.)
A used part, in service, is a proven part.
Any new part could be a Monday, or Friday product, and is unproven.
Of course there are always options.
1. Wrap that replacement belt in plastic and carry it, along with tools necessary to make the change on the scooter in a storage bay.
2. Replace the existing belt with your purchase, and do as above.
3. Don'tworryaboutit! Enjoy riding that scooter, especially if you are a local rider/carry a cellphone. Or enjoy meeting new people.
4. Spend more time washing/waxing/tuning/maintaining/photographing your prize scooter than riding it.
IMO, if you have not noticed performance degenerating, it's probably acceptable.
I am operating a 30 year old scooter with only 3k miles on the meter.
The clutch was noticeably grabby on startup, and the belt 'strummed' a bit.
All that has mostly subsided now that I am running it at least every other day.
I have no clue if the original belt has ever been replaced. Perhaps I should open the case for inspection ?
I have put thousands upon thousands of miles on visibly cracked serpentine belts in automotive use that showed wear on the sides, and the backside where they drove various sheaves. Never lost a belt.
Pls take my opinion with a grain of salt.
redk