In an asymetrical connection, the speed is set by the slower partner. So, if you are a T3 and you connect to a 56KB modem, your maximum download speed is 1KB/s regardless as to the number of other slots that modem may have. The number of slots simply determines the amount of bandwidth allocated to the upload function. Self evidently, if there are many people connected, there is little bandwidth available to be shared between the clients.

Later post script

Out of guilt, I decided to run another test as an ultrapeer using LW 2.9.11 and the performance was no different from the last using 2.9.9. I spent about 40 minutes watching the spinning wheel of death before Limewire crashed. My experience therefore continues to suggest that Mac users should stay as a leaf. Although I am tempted to try LW3.0.1 which I understand is now out. Hmmm. Perhaps, I'll go run another test.