The only way to keep brake bias in an electric would be to keep the 2nd servo for mechanical brakes, and parrallel it with the ESC throttle controls. There is simply no room, especially in an 8 to fit in the motor, giant battery, big ESC with fans, AND keep a 2nd servo in place. I'm already having problems fitting in my MGM speedo after mounting a fan on each side. The provided plate that RC Product Designs has as part of the center diff top plate is too small for me now, and was bending under the weight of the ESC by itself, with no fans, under the impact of landing from 20 ft in the air. I'm going to have to fab a new mount to sit just above the rear driveshaft and chassis brace, behind the battery to mount the speedo.
Oh, and as for needing a slipper clutch to control the wheel spin, etc, we already have that. It's called the accel setting in the speed controller. I can set how fast the motor 'ramps up' when I punch the trigger. Why would I want a mechanical slipper clutch that wears out, loosens up during the run, adds weight to the drivetrain? The best reason for going electric is to eliminate the 'consumables' like CLUTCH PARTS! I'd much rather have a new center unit that's full time drive to the rear wheels with a one-way bearing drive to the front. That will give you ALL the brake bias you need to slide the back end going into a turn.