I've been using mobile internet for last few years and whenever i would try to seed it'd be like 0.2 kb/s at best. I know that it's due to my dynamic IP (or whatever it's called) and i have closed ports.
Then i saw some people say that opening your ports makes your connection better/faster because you're able to connect not only to people with open ports, but closed ones aswell. Does it make sense download-speed-wise? Because how could i take traffic from someone who's unable to seed due to closed ports?
I'd have to see it in the specs, but if you open the inbound port it would allow someone who got your address from the tracker/DHT to proactively connect in and feed you data. More peers = more speed each little bit helps. I don't know if the announce to the tracker specifies 'I need parts A, B ,& C' where peers could connect in offering those if they had them, but it would only be possible if the inbound port is open.
Where defiantly does make a difference is on the seeding side 'I have it all, 100%, come get some' only works if the door is open.