While I have no issue with my iPhone 4s staying connected to my AT&T Microcell, my battery does drain quickly when connected to it and if Cellular Data is enabled - disabling Cellular Data resolves the battery drain issue.

I've filed a bug with Apple at https://bugreport.apple.com/ and had an engineer request a number of logs from my iPhone 4s while connected to my Microcell - I would encourage all of you to do the same!

Bry