LOTR--here's an old link re bandwidth capping, but it does cover most of the arguments.
http://slashdot.org/articles/03/09/22/1744232.shtml

btw--if you run as an Ultrapeer, keep an eye on the bandwidth: I'm seeing up to ~15KB/s (can lead to about 1 GB/24 hrs). This used to be about 1/2 as much, but has been creeping up in the last few months as far as I can tell.