I always thought that all boeing autobrakes used a fixed braking force for a given autobrake setting, not like the bus which will produce a fixed deceleraton, modulating the brake force if reverse is used.
Please correct me if Im wrong.
Putting the shoe on the other foot -
Wouldn't it be nice if power management for TO was always set to achieve a known acceleration rate, based on R/W length and Vr (or some other speed)? You'd never be in coffin corner for TOGW error, brakes dragging, etc.