Well, I am out in the wild with my Pro1x. T-Mobile seems to have gotten better here. I seem to still be using band 4. Call was fine. Using internet on data now, no wifi. It's slow but steady. Even downloaded Firefox. As I said, slow but steady... no balking and quiting. I am wondering if US problems on T-Mobile have to do with which bands T-Mobile is relying on where.
Or if there are defective units, as @EskeRahnraised, is it many or just a few? Any are too mmany for those that have them, I understand, but if weren't hanging out at this forum, I wouldn't see any reason for testing.