I own 3.x and am quite satisfied with it but for one thing: the restriction for one computer. I often have my laptop at home and on my LAN but it's just me that uses it. I put it on the LAN to sync files to my desktop quickly. But since SD is in the login items of both, I always get a dual - use warning and have to quit one. It's supremely irritating and insulting. Those companies who really want to restrict uses on a LAN should at least have a limit of 2, not 1. For that reason alone I wouldn't pay any upgrade fees, until that restriction is removed. I'm also not especially pleased about the 3.x -> 4.x upgrade as I don't know what else is really needed! But that's another matter.