i must admit i would try this just to say i did it....then ill hurry up and get back on vzw before i drop a call.
Haha to be fair to AT&T...I was a long time AT&T user, no not for iPhone and their service in my area was just a bit better than VZW. When I am in Grand Central waiting for train to leave I would have service with AT&T and none with VZW. The data speeds were also a bit better and never had a problem with dropped calls. In and around midtown manhattan data speeds did slow down but that was from everyone using the metoo iPhones...
I may have not left AT&T when I did if they did not take away my unlimited data package and then claim they can not give it back but I am sure I would have left eventually since they went from the carrier having the best phones to carrier having worst phones...