http://www.limewire.com/developer/GDFDoc.htm
Limewire has done a study on this and there is merit to it... but the problem lies in how often do you broadcast the files to everyone...
I think that allow the network to organize itself with clip2 reflectors may provide a nicer solution to this. Then you have 2 different cache hosts 1 for high speed and 1 for dial up. All of the people on dial up will ping a cache host of people running reflectors, all high speed users will ping a cache host of other high speed. The reflectors automatically answer queries for other servants. If you included these reflectors in all servents and then setup up the proper defaults for dial-up and high speed connections that would reduce the network traffic a lot... especially since the dial-up users very rarely are the ones actually hosting files so they wouldn't be answering unnesscary queiries.