Whenever this topic comes up...and it does frequently...I find the same thoughts run through my head: If you worry about maintenance costs or issues, the M3W probably isn't for you.
It's not about practicality, it's about pure pleasure. The M3W is best enjoyed by those whose primary focus is the experience, best if one is afflicted by Non Compos Mentis. Logic gets in the way.
If you want to be left brain for a moment, the issue might be not so much reliability but service: Find out how often your dealer has a functional service dept..how many techs and how often are they at work, what's the average wait for an appt and how long is a "Typical" service?
I can tolerate gremlins much better than I can tolerate the wait for exorcism.
And comparing a Cayman to a M3W is like comparing mustard to daisies. The closest car I have.... a 4C....a delicious confection that is as "Pure" in its way as the M3W. yet the overall experience is totally incomparable. Sell the Cay b/c you don't like it or you're just done with it, not b/c you think the M3W is "Moving on"...
The M3W exists on a totally different plane of reality.
If the 4C ever gets a third pedal, I'm on it.