The Rotterdam class can only operate Medium sized helicopters from her deck.The Galicia class can operate heavy sized helicopters and even V/STOL aircraft. I guess it depends on what the RAN is looking for. With Army having CH-47 i would assume these helicopters would want to operate off any future LPD the RAN may purchase.
That is,if the RAN wants a future LPD.
The Johan De Witt is an enhanced version of the Rotterdam. I'm pretty sure it can operate heavy helicopters like the Chinook, as that was a modification done to this 2nd vessel.