I am not so sure about "marginally". The Marines wound up with 3 BAR's per 12-13 man squad at the end of the war.
The BAR simply cannot provide high volume fire without wrecking the weapon. Not only does the BAR provide only about 60-65% of the fire of a Bren in a measured sustained fire role ( not really done in combat?) but should a high volume of fire be needed for several minutes (say 200 rounds per minute or more) the BAR's barrel can be destroyed or the gun itself and not just the barrel can overheat. Melvin Johnson destroyed one in a test in about 700-800 rounds. Fore end on fire (visible flames and not just smoking but it may very well have been one of the older ones with the big fore-end) and main spring (in the butt) lost it's temper and the gun stopped functioning. Very extreme to be sure, but a Bren even if the barrel is not changed according to the book/drill and the barrel ruined can be "fixed" by the squad in about 10 seconds. The BAR equipped unit needs to draw a new gun from supply.