I actually had something similar on my old Rover 827, brakes juddering really badly through the pedal. Turned out that it was the ABS firing, and the cause was an ABS sensor mount had corroded on one of the front wheels and was forcing the sensor away from the ABS sensor cog on the wheel so the system thought the wheel was locking up, hence the system firing and subsequent judder.
A trip to the breakers for a new sensor and all was good.
As for warpage on road use.... I used to get that, again in the 827, with standard discs as it was a heavy old tub, and if you left the breaking a bit too late they got very hot and warped badly. Went through three sets of front discs on that car during the few years I had it!