Doesn't the number of people who are on the network determine the speed? E.g. more people = lower speed.
I live in a sort of rural central Florida. Not even Sprint or Verizon have good 4g coverage here, so I was extremely surprised that Metro did. I'm sure not much people know it exists. Like people at my college are often in disbelief that I have 4g.
My speeds are usually between 2mbs-4mbs at home, but increases the closer I am to the center of the town (better signal).