Traded our B Max in today for a Honda Jazz.
I had the clutch replaced last October, and at the time of typing this there have been no obvious problems with the car since then. However, I've lost confidence in the vehicle and don't want to be contemplating a large bill if the clutch goes wrong again after the Ford warranty expires this coming June.
On the positive side, the B Max is a great car, a wonderful drive and a masterpiece of small car design. I certainly wouldn't eliminate the possibility of buying another, non Powershift example some time in the future; perhaps a late Ecoboost if low mileage examples are still around in two or three years.
In the meantime, many thanks to all those who have shared their experience and advice with me, and good luck to B Max owners everywhere.