Assuming a car has good ABS, is EBD only beneficial for inconsistent surfaces (e.g. patches of gravel, oil), or is it still beneficial for high quality roads?
Also, is it helpful while braking through a turn?
EBD is the most important part of the braking system. You can have ABS or not (older cars did't have it) but you can't drive without EBD. Older cars were equipped with the mechanical brake force regulator that has similar functionality as the EBD nowadays. In short EBD is responsible for keeping the rear wheels from locking while braking. The rule is that you can have the front wheels locked it will just make the braking distance longer (and the car won't response for steering) but you can't have rear wheels locked because it will make your car immediately turn around. The same happens when you pull your hand brake and lock rear wheels.
So EBD is the part of the ABS, they are not actually separate systems. It's just the name of one of the functions that ABS does.
And do ABS (EBD) help while braking through a turn ? Of course it does. It was invented mostly for this purpose (to let the dirver turn while braking).
PS. Sorry for my poor english :)
EBD is better understood as Electronic Stability Programme(Anti Skid). Any given wheel sensor of the ABS(Anti Lock) will determine the slip angle of the wheel its on. Slip angle is basically the difference between the speed of the individual wheel and the speed of the vehicle ie. lockup. Weight transfer to the front of the vehicle when braking would normally permit the rear wheels to lock up, the ABS would stop the lockup from happening. The maximum braking of the rear wheel would be maintained to the point of locking up. EBD/ESP will take a reading from the steering angle sensor of the vehicle together with a reading from the lateral yaw sensor and deceleration sensor, compare it to its 'map' and then apply the brake to a 'single wheel lock up and release' to bring the vehicle back onto its implied direction from the steering angle sensor. A system such as ABS and ESP, which has been universally adopted as it has been, must in itself prove its viability in road safety.
@Allan Osborne. You probably confused ESP with EBD ! That are two different systems and andrewb asked about EBD. EBD was developed to replace mechanical brake force regulagor. This is critical piece of every ABS system. And ESP that you are talking about is additional system that prevents a car from drifting. And as long as either front or rear wheels do not start to slide this system does nothing and I don't see any reason it would help while breaking through a turn.