I happened to test drive a 5GT this summer, it's a nice car, good view because of the seat height, and pretty good driving feels for a car in this dimension, which probably has more things to do with the smoothness of the engine and gearbox. oh, and the steering wheel size is funny compared to the size of the car, not in a bad way though, but you know.. funny...
Not bad to drive in city and cruise on highway considering you're getting a chassis from 7 series, with a price tag of a 5.
But I saw the reality When I did a U-turn, physically it's still a big wobbly car. The same driving experience might hold true for the 3GT.