I used to have 512 broadband, which i always maxed out at near 60 speeds on torrent.
I just got a new broadband service which is syncing at 5MB (speedtests show 4.5) and I can't break the 20 d/l barrier. on the other hand my uploading is working just fine.
Using Azureus but tried BitComet and BitTornado.
edit: My torrents are all sourced by near 80 seeds