Regarding the tit-for-tat rules of torrents -

Do I understand it correctly that if I upgrade my line's upload capability from 512kb to 1mbps (but leave the download speed at 3mbps), this would generally increase torrent speeds (by how much?) given that I would be able to provide more downloads and thus gain more 'credit' from other connected peers who would then increase their upload rate? - the same reason for not having too many upload connections per torrent...

My ISP provides 3-16mbps options, each with a standard 512kb upload upgradeable to 1mbps. The 3mbps/1mbps up is more or less the same price as the 5mbps/512kb up.