I agree with Mike pretty much , though I also doubt that there is a bulet-proof way for rating that can not be faked.

Since I am following the discussion here, I think somehow that we talk about 2 things: One is bandwidth the other is how to "do something against freeloaders" ... and I don't get the point what the two things have to do with each other ... at least freeloaders do not cause are "needed" to keep the network together (though they might lower your effective horizon cause of "unnecessary" hops = freeloaders in your network path).

I think the bandwidth problem is a Gnutella Protocol issue not a freeloader issue ...

So if I get you here you wanna send the queries (incomming/outgoing) to the first list. Do you want to connect to these hosts as well? I mean then you might eliminate some freeloader paths" in your horizon. I mean then one could close the connection to a potential freeloader and ( I am brainstorming ) that could leed to a new network structure where freeloaders are cut out by time if all clients act like this. On the other hand how do you want to rate a client whether he is a freeloader or not? I mean someone might provide files that you are not interested in at all though others might be?
Another thing: cutting out those who do not respond to your queries may lead to a "smaller network"/ smaller horizon for your client but this smaller horizon may have more clients with files you look for ... or am I fascinating totaly now ?