Generally speaking, I don't think the experience would be as bad as you say. Yes they get the lowest priority but given how good AT&T's network is, you generally won't be kicked off and would probably incur a reduction in speed. The reality is, you aren't going to need (insert super fast speed here) on a day to day basis. There are exceptions of course, such as tethering or streaming content, but really, how often would you be doing that and need it? This is why I don't buy the 4G argument, especially when there're carriers that ask us to pay more simply to be on 4G.