Veil Guy,
I love the C4S and it does handle at a higher level than the M3. I believe the reasons are:
1. Much larger tires. 305's in the rear.
2. Active suspension
3. 4-wheel drive. The fronts pull a min of 5% and a max of 40%. So, not only is it being pushed from the back but also pulled from the front. This creates very little understeer.

The M3 is an incredible automobile however I give the edge to the C4S when it comes to cornering. The M3 SMG can shift much faster with the paddles and that puts if pretty close to the C4S in acceleration.
M3= 333HP C4S= 355HP Both weight around 3400 LBS.

The bad about C4S is there is very little room to carry stuff with you. The fwd trunk in even smaller than usual because of the forward drive mech.

In a perfect world I would love to keep both but I can not justify it. Neither would see action in bad weather and in good weather the Cab would be my typcal choice.

As for convert? I had a 99 996 Cab before the M3 and my heart has always leaned towards Porsche.

Sorry but I don't see driving to Florida for testing with my schedule and would rather not jack that many miles on the car.

Walt