Going on the previous generation alone, I purchased the
JCW brace for my Cooper - it was an excellent piece of kit which really did make a diffference to the feel of the car.
I recently upgraded to the GTT braces though, and they are better still.
I wouldn't compare the
JCW brace to string for instance, but due to its three piece design, it's certainly not as rigid as the GTT brace. It's still good in its own right though.