Regrets - I've had a few ......

Seriously though I suspect I won't miss it too much until next spring now.
Comparisons:
Performance: still running in the Roadster but its going to give me an even bigger kick in the back when I boot it.
Handling: Very little roll on the Roadster and not much in the M3W, but the formers stiff front end allied to an extra wheel is going to give greater confidence in corners.
Steering: After the M3W (and our Mini) found I had to wind the wheel noticeably more despite the now standard power assistance. Its just a matter of adapting though.
Comfort: Roadster has surprisingly stiff rear suspension noticeable on Norfolks bumpy roads, but may loosen up a bit. The M3W had equally surprising soft rear suspension with plenty of travel although the cockpit was more cramped. Nice to have less concerns for the weather with a hood available, allowing greater use during the winter.
Sound: Little to beat a stage 1 M3W. The Roadster is whisper quiet at idle and low engibe speeds but promises an awesome snarl as it hits 4000 rpm.
Attention received: Getting an equal amount at the moment but the M3W would win hands down at a motoring event.