Hard to cross shop these two cars given the price difference and number of seats. To me, the M2C makes a great DD, the GT4 less so. From a pure driving experience, I'm sure the GT4 owns the M2C, as it should for the price. For me, all the Porsche GT cars are wasted if you are not tracking them or at least able to take them on spited back road drives frequently. Sure, it's cool to putt around in city traffic with a nice car (if you are into that kind of thing), but...
If anyone was offered either car, I cannot believe any sane person would not take the GT4, if only because it would be easier to buy an M2C as a DD.