I had '06 fully loaded MCS JCW, now driving Z4 M Coupe. I bought the M Coupe because I crashed my MINI. If you ask which I like the best I'll say both. I would like to have both. However...
The regular MINI Cooper S is fun to drive, but the JCW is a blast. The M Coupe is different. It's easy to drive in streets maintaining low speeds, but when it comes to having fun, turn off the traction control, push the SPORT button and a beast is awaken, now all you need is to know how to handle it.
My JCW was more agile and nimble, however it ran out of juice very fast, where the M Coupe seams to have endless power and maybe better corner handling. I haven't taken my M to a track or autocrossiing, so I can't provide with a better comparison.
I of-course miss my MINI, but love the M Coupe. I test drove the Cayman S before making a decision. Even though many reviewers have given a slight advantage to Cayman, I like the coupe much better. The way it feels and responds is just what I wanted, plus: It's absolutely fun to drive and it is so unique and rare.
I will definitely say YES, go for it and you won't regret!