That would be annoying. Still, though, it wouldn't change my mind about this topic.
Your mileage may vary though. It is pretty good in cities. Do you travel out in the middle of nowhere much? T-Mobile might not be the best for you. When I think of satellite phones, I imagine being in a situation that would require me to call for rescue.
I quoted the $70+ figure because you use 3 - 4 GB data per month. You will still keep unlimited data without throttling.