I use utorrent on osx because I liked it from my windows box. If you have access to a windows box on the same network I suggest you use utorrent's speedguide on windows to properly configure your settings on your mac. That is the case I had to do to get 1.1~1.8mbps. I use ubuntu and/or open office p2p downloads to test max speed. Usually end up seeding 2~3:1 ratio since I feel kind of bad for using up bandwith 😛