Just for the record: I had the BK brake fade thing, too. Got the ESC replaced, and no more problems ever since. Not a trace of brake fade on my trucks.
I like the cleannness of no-mech brake setups on buggies. One less servo, and also the "cluttering" Mike mentioned.
I still have to test my MBX5, but I was told the ESC brakes in combination with a center diff should work well. I'll let you know.