Basing a sharing system on bandwith alone is flawed in my opinion. On 512/128 Aussie DSL I cannot compete with US and UK based ISPs where huge speeds are possible.
As part of the WinMX community I have been judged I believe by what I share, not how much. I share things I have that other people may not be able to get.
That is what Community Filesharing is about. Sharing to the best of your ability.
Otherwise lets just set WinMX up to ban 56k users, and possibly slow DSL speeds like mine, lol.