Oh, here we go with the 5GT bashing again!
Think globally. The US might not like it, but then the actual sales figures for the E61 demonstrated that Americans didn't like Tourers either. In 2011 the US was listed as the third biggest market behind Europe (excl. Germany & Britain), and Asia. It's not all about keeping Americans happy. IIRC correctly the E61 did ~1800 units in its BEST year in the US. 5GT has done ~50,000+ units globally so far. Maybe BMW's mistake was not offering the F11 to the US, and loosing out on those ~1800 units, but by adding the GT to the range they gained ~50,000 units.
You're getting the F31, having the 3GT alongside it in it's European and Asian markets can't really hurt, can it?