@MrMazda It took me ages to work this out, driven mainly by wanting to know why I couldn't snatch torrents with one or two seeders no matter how long I connect to them, and noticing people waiting indefinitely to leech torrents I'm the sole seeder of.
I have a feeling it's something not that many people are aware of. I was going to post an explanation, and kinda one-off workaround guide here, until a long discussion with my AI friend taught me that there are a couple of other "must have" factors which complicate things further. For the time being, I've stepped away from the idea, at least until my head is no longer at risk of exploding!
Just a thought: Since the ability to port forward is so integral, and there are few VPN providers who allow this, might it be worth the site listing somewhere a few of those that do, perhaps with more in depth "this is the advantage of this one" info? I'm sure some are likely to offer "refer-a-friend" or "associate" type financial rewards, so this might generate a small income stream to help defray the costs of providing and maintaining this site.