I have checked the temps of both discs since they were changed and cannot feel any difference between them. As a thought, I have had this differential wear on the drivers side front compared to the passenger side before on several cars and always put it down to most of the mileage being done with just me in the car ie to work and back. when you think about it with modern systems there should be even distribution of brake pressure to prevent pulling to one side or the other or is there different inertia characteristics with the weight at one side? Its an easy explanation or is it ?
There may be a trend showing up here but I have not got time now to look on Vectra sites to seek some confirmation.

The way to true enlightenment is not to work 12hr nights!!!