Despite the fact these are still road cars, in the context of a GT4, the 6 makes more sense to me. Personally, I'd be more interested in a turbo engine (4 or 6), as I buy these cars for street, not track. But the target for the GT4 is clearly Track Toy with a pair of capital Ts. Were I still in that market, I'd far prefer an NA engine making power high, rather than a turbo generating torque low. Just more fun which after all is what going to the Glen, Mosport or VIR is all about. That said, a sub 2800# 550hp turbo 4 Cayman with enough lag that you have to count to three would certainly be entertaining. Probably kill too many customers though... likely me.
Regardless, it will be interesting to see how Porsche manages the GTS vs GT4 performance envelope. Be a bit embarrassing, if slightly tuned CS/GTSs wind up blowing by new GT4s on back straights all across the country.
2017 Cayman S
2000 911 C2 Brumos B59 Special Edition
1970/73 911 RSR 3.2 Clone