We upgraded from a Popup to a TT a month ago. The thing that made us not really look at 5ers was that we normally take 4 bicycles, and 4 kayaks. With the TT I have the bikes in the bed of the truck, and the yaks on a ladder rack above them. I saw no way to carry all that with a 5er.
We went with a Blue Ox Sway Pro, and it pulls fine, no sway. From what I've read the hitch makes a huge difference. Thanks to all the info on these forums I think it helped me make the right choice on the hitch with out having to upgrade later.