Can BA negotiate a better deal with Hilton. 500 miles/stay really doesn't compare to 1000 miles/night for up to 3 nights.
Presumably Hilton pays BA per stay and bmi per night. The bmi earning rate really did encourage me to put more stays the way of Hilton. The BA rate on the other hand gives me no incentive to stay in the Hilton over any other chain.
Even if they change the 500/stay to 500/night I'd be reasonably happy.