I will say something about SPRINT. First off, that article is WRONG!
Baltimore, Maryland is the 1st SPRINT test market for 4G, but it's not even mentioned in that article! I know so because SPRINT is actively advertising it and it's been in other press reports. So how many other test markets did they miss in their alleged comparison of 4G vs. 3G I wonder?
Um, all of them, I guess. That test was carried out locally, since the local city, at that time, provided "4G" from the 3 tested providers. I'm not sure why that would be a problem for you. The only issue I have with it is that Tmob is not tested to cover all 4 national providers, perhaps that wasn't up and running in Detroit at the time. Maybe you'll like this?:
http://www.rootmetrics.com/pr/reports/2011/20110320_Seattle_4G_Study.pdf
So, what magical speed does Sprint offer in Baltimore? Considering that they only claim maximum 6Mbps speed for their "4G" network, and that was achieved in the test, you shouldn't have any problem with it.
"4G" is the problem. As marketed:
Sprint: up to 6Mbps
AT&T: up to 6Mbps
Tmob: up to 21Mbps (however, I never see test reports breaking 8Mbps)
VZW: up to 12Mbps (but test reports show higher speeds)
Do you see anything amiss in the use of the same word for all that?