

Find two more selfhosters and they will criticize both of us!
Absolutely. However I’d argue that some BSD variant is at the other end, not Gentoo, so there’s at least some critics to you ;).
I’m running proxmox and (mostly) Debian on top of that, and I’m sure that there’s someone thinking I’m doing things the wrong way.
With Windows Servers I think the bigger problem is that there’s way less people running things on top of it, so there’s less knowledge about problems and solving them. However, many of us are on corporate IT jobs too and thus have to work with Windows, so that might somewhat cancel out the difference in popularity.

I would just keep it simple: “Self promotion for your product is allowed, but this is not an advertising platform. Be sensible and participate to community. Abuse will result in post removal.”
I don’t think it really helps to place any arbitary limit as it might just result on spamming low-effort comments so that your “quota” stays under the 10% rule and also posting about your fantastic FOSS project daily could be equally annoying. That 10% rule could be useful when deciding if something should be removed and obviously free projects should have more relaxed “limits”, but in general what counts as abuse can be decided by community feedback.