Greasy Fork

I chose GF as the main site for the scripts because of the meaningful statistics, and probably many other devs for same reason, why not to make this strong GF's side even stronger with more statistics, like the visitors of the script's page, something similar to GH's traffic:

Would allowing authors to include Google Analytics code on their script pages work? I suggest GA because the site already uses it, so there's not much more downside to including another account that gathers statistics.

Not sure if there's any problem with having two GA accounts on a single page, or GA on a domain you don't control...

I agree but that wouldn't work for me. I prefer to have a greasy fork built in feature for this.