OK , lets break it down , why wud it be the caliper or the whole front brake system ? The components are used on other vehicles without a problem , for example the Skyline R34 GTR ,a much heavier car, do we know of a problem there? I don't. You are having problems with other disc's , are these disc's similar in design to the Brembo disc , excluding 2 piece with alloy bell which obviously arn't.
Cud there be faulty calipers out there , remote I know , but has anyone checked ?
I approach it this way because the problem seems to afflict drivers of all types , moderate to extreme , in many types of conditions and then some cars are completely unaffected , so there has to be an esoteric reason for the problem , not simply a crap braking system , which it isn't.
Remember also that no magazine test has ever commented on a) poor brakes or b) brake problems , and these guys really push cars to the extreme.
Really I don't think that the braking system is inadequate , and I also don't think that it is neccesary to replace the system with 6 piston AP kits to cure the problem , more investigation is required , preferably controlled tests with detailed data aquisition.