Given the Roadster was introduced to replace the original +8, if the book on +8s is to be believed, perhaps a 3 way comparison would hve been even better.
The evolution seems to be:
Trad + Trad V8
Trad + modern V6
Aero Chassis + Modern V8
I'd like an Aero chassis with a V6, for me the BMW V8 is just too much power. But the Ford motor wouldn't gell with all the BMW electronics. The BMW straight 6 would be perfect in an Aero but after measuring it in my sons 330 CSI M Sport as far as I can measure it the BMW straigt 6 is too long. Sad, it is a wonderful motor.