Not all 737's have carbon brakes. I beleive that the NG's do but that in the classic they are an option. At least our 300's do not have them...
In the scenario of an engine failure before V1 and a limiting runway I cannot see how you can have your heels on the floor and yet do a max effort braking. You will need nifty footwork just to keep to the centerline, specially with asymetric reverse. At wich point are you going to be able to lift your feet from the pedals to find the brakes?. If the autobrake does not operate it is going to get very interesting, in any case max braking is always manual.
Any other views?