Don't upgrade to the BitTorrent 3.3 client. At least, not if you like to have more than one torrent open at a time.

It crashed my modem at least 3 times in a row when I had about 4 torrents going, plus I noticed that it really slows down the system since it doesn't allocate the files ahead of time.

I do like some aspects of it, but the fact that I can't see how much of a file is distributed, how many seeds there are and can't fiddle with my upload/download ratios doesn't make it a winner to me.