I've never had a problem with shared boxes personally, they offer decent speeds at an economic price point for many users. That being said, I have sometimes felt concerns over the shared I.P. address commonly used. For example, what happens when another user on the box with the same I.P. is using it on the same tracker you use, or perhaps even the same torrent? I've personally never had an issue from this on the trackers I currently have.
But dedicated boxes are nice, for more then just additional speed. I've never purchased a dedicated "formatted" seedbox per say, but I have p