I mentioned this a lot when the 2015 Mustang was previewed - I didn't understand keeping the base V6 when the 2.3T was so close in power. As Oliver will be quick to point out, I understand that it's a great way to get more use out of an old engine, and certainly works wonders for fleet vehicles.
I don't think the 2.7TT is a great engine for Ford cars (Trucks, perhaps). Its power is not up sufficiently compared to the 2.3T to warrant a second turbocharger and two more cylinders, and quite frankly, it sounds like its application is intended more for heavier vehicles where the 2.3T would be too far taxed too often.
I don't think Ford got the marketing wrong for this, but power out of the 2.3T really should have been closer to 330-340hp to differentiate it more from the base V6 rather than downrating the V6 to 300hp from 305hp. The 3.7L V6 got that output on regular gas, whereas the 2.3T recommends premium for max performance, by the way, so if offered a 2015/2016 V6 or a 2.3T Mustang as a rental car, I'd take the V6 because it'd have moar powah by virtue of the gas it is filled with (rental agencies specifically tell you to use regular gas).