Sell my Z for Alfa Romeo 4C?

ZCanadian

That is what this is for:
CG-Lock for Adults - CG-Lock.com

As the driver, or passenger? I find I'm tucked in pretty good but the dead pedal gets a workout and occasionally my knee on the door panel when I'm on the track. Passengers can get chucked around pretty good, though.

Might also depend on which seats that the car you tried was equipped with.
I only have experience with the "racing" package seat - leather with microfibre inserts. Pretty grippy, but still the same shape as the straight leather and the basic cloth versions. The shape is definitely a compromise between comfort, weight, and containment.

To get bigger bolsters, you give up a lot of room for getting in and out of the car. I think that's why it is the way it is.
With the long door, enormous sills and fairly forward seating position, if there is ANYTHING at all next to the driver's side preventing the door from opening wide (garage wall, parking garage column, other car, or even tall curb), you could not get into the car if it had better bolsters (unless you change to a removable steering wheel).