actually since posting above I've been reading up on Gasoline particulate filters (GPF). It seems they will differ considerably from the ones fitted to diesel engines. As petrol engine exhaust temperatures are much higher than diesel, apparently the cars will not need to do active regens as it will regen on the fly as soon as the car is up to temperature, (which is very quickly), and apparently the regens will finish much quicker than on diesel engines. They have basically said it will be pretty transparent to the average driver, and won't actually affect the use and mileage of the car at all.
About the only downside is the extra tech on board (which is something else to go wrong), and I guess there will have to be another price increase to cover the expense of the tech ?