Simon,
That depends alot on the car in question, as different race formulas have different brake setups. Regulations some times force a braking setup that isn't the optimum, as with tyres to keep track speeds down, and in theory safety high.
As for your comment about driving - well! Driving at 10/10 has nothing to do with locking up the brakes - as I said, the better the driver, the less he uses the brakes. Good fast driving on the track is about keeping the car balanced at all times, and limiting weight transference - locking up your wheels, implies braking v. hard, implies bad balance, implies not driving at 10/10s, but driving badly. The better the driver I have become, the less I have locked up the brakes, not the other way round. Braking is always in a straight line, firm but progressive (apart from trail-braking of course!). ABS would definitely be a hinderance. With the current braking setup, I can accelerate/brake where other people have to balance their throttle, simply because I can firmly get on the brake, and quickly get off it without upsetting the car's balance. ABS would have kicked in and prevented me from getting on and off the brake quick enough.
Of course you could also come to Donnington on 31/10 or 19/11, or Goodwood on 12/11 and I will 1)Take you round, and 2)Let Ed Moore (ex-Formula Ford champion, and current FF racer) take you round. Ed is obviously much quicker, but I am not exactly slow!
I 100% agree with ABS on a road car. Switching the subject v.quickly - did anyone see the CAR magazine incident when they crashed a Tuscan in Wales (into a wall no less). The said - oh, if it had ABS, we would have been ok. What crap! Driver aids are only driver aids if they contribute to making the car quicker, they shouldn't be a subtitute for driver skill. He crashed the car through crap driving - cars don't crash themselves!
Monday - at Croft - there was a big off - it was a Skyline GTR-33 - the car which has so many driver aids, it nearly drives itself! The guy crashed within half an hour, hitting armco and everything, locking up etc. - drove the car badly. The two fastest cars on the circuit? Mine, and a race prepped Caterham - neither with ABS, but both with good drivers!
This whole topic is within the context of a RACE PREPARED 7 not a road car! I suggest ABS won't stop people crashing if their driving is crap in the first place!