re: Stief
You're correct I'm behind a router and most of the time I use os X. However I've fowarded the gnutella port + I have forced IP. Also, note that my router is a Linksys with the latest firmware, which is a big factor IMO. It is true that a router can be easily satured by lots of incoming connections, I think that cheap routers don't have enough memory to keep the pace of connections.
It does a long time since I haven't been an UP because I prefer share my rare stuff on the 160kb/s sympatico upload speed...
I'll do more tests and be right back.