I really hate, when someone downloads 5GB from me and let me download only 200MB. I think it would be very nice if KTorrent allowed upload speed to be only as high as download speed (with some configurable tolerance perhaps) per peer (not overall). Also it would be nice to specify maximum download/upload speeds per peer.

You can help to reduce that problem by lowering you number of upload slots. The tit-for-tat algorithms will focus your upload bandwidth to those who are actually providing you with a measurably relative amount of data in return.

most connections are asymmetric so I can dl much faster than i can upload to you, as a result i have to seed to you/whoever still wants the torrent for a couple of days after im done, your suggestion would cripple bittorrent protocol and likely get ktorrent banned from many trackers if people actually used it.