This applies to front PTO shaft driven decks: the brake on front PTOs is to help stop the belt revolution once the idler pulley is released. Start the deck drive, the brake is off. Turn the deck drive off, the brake is on.
I may be making a mod to the front that will make it necessary to remove the brake. I'm not sure I see any particular reason why this would be a problem. Yes, the blades might spin a bit longer without the brake than with it.
Anyone see a particular problem?