I have a 3.0 litre Roadster from 2005, and a 2016 Plus 4 with the AR chip and manifold/cat/exhaust.
On the road there really isn't much difference. The P4 is lighter, and more nimble, and can be pushed harder at the limit of adhesion.
My Roadster excels at A road overtaking with effortless acceleration, but the P4 doesn't give much away.
The 3.7 is obviously quicker.
Try both if you can.
