No credit system, please. If somebody really wants to be a freeloader, let him.

I don't make the design decisions at LimeWire but I'm quite sure the LimeWire developers would agree with me there (for a change). Freeloaders are not a serious problem at the moment. People downloading lots of files are usually also sharing at least some of their downloaded files.
Partial filesharing doesn't work as well as I would like it to, but that's one of the points where I disagree with the LimeWire developers.