Fonz
You are right in as much as the 200 does not require its operator to hold a High Capacity AOC whereas the 300 & 400 does. Unless things have changed, its the AOC (and its accompanying CAR 217 organisation) not the aircraft which dictates the pilot experience requirements. That is to say that I don't believe there would be any problem with 'stepping back' to the 200 as long as the aircraft was being operated under a High Capacity AOC.