The mole weight of the compound went from ~280 to ~480mg, and the propellant is not as forceful. Additionally, because of the 'new' formulation, it is again a proprietary formulation, so there are no substitutions available. Albuterol with CFC retailed at under $20; ProAir©HFA goes over $40.
~280 to ~480mg should be micrograms, µg Sorry.