Like Barry we have a launch edition P6, however unlike Barry we have had both the brake master cylinder and the radiator fail. But we have just returned from a 4000 km tour and I must say that the brakes are now great (there were moments when I forgot and pushed on the brake pedal such that we came to an abrupt stop!). And no more radiator problems.
When one looks at the location of the radiator and swirl tank connections then it is always possible for problems when servicing - just another problem of being in the motor trade!
So in the case of our Plus Six just a great car made BETTER!
Kerry