I've changed mine many many times to cities all over the country. Nary an issue.
That's strange since 3 different Millenicom reps have told me the same thing on the phone. Actually though does changing it really make a difference if you are static and not traveling around?
Sptint speed tests:
Atlanta:
Chicago:
Ft. Worth:
I think if I relocate the Franklin to a better spot then the upload would be a little better. Since you change your HA settings are your speeds a lot better than mine? If they are I will persue getting the info from Millenicom or Franklin.