[quoteThe airline I work for suggests that that consideration be given to NOT setting the park brake after completion of an RTO][/quote]
From the B737 QRH. "When the aircraft is stopped, perform the procedures as required...consider not setting the parking brake unless passenger evacuation is necessary."
Despite this you need to consider runway slope, and the fact that even at idle thrust the aircraft can move forward under its own steam as it were. There will be a lot of activity in the cockpit after a high speed rejected take off. And especially at night and heads down reading a non-normal checklist it may be difficult to sense the aircraft is slowly moving if the parking brake is not set upon stopping.
Don't know the answer re carbon brakes though.