IMO, that's BS right there. If the company considers the Q FO the top of the FOs and Saab FO better than 1900 FO, they should have different pay rates. Since they don't, then they should be considered about equal, thus not restricting moving back and forth between the three for QoL, commuting, whatever the hell the pilot wants to do issues. Restricting guys and saying they can't move "down" to a position that is essentially the same job and even pays the same is just covering for lack of management planning. It would be like our management saying you couldn't go from the -900 to the -200 b/c the -900 is a step "up." Reality is there's a seat lock, but it's b/c the -900 is treated as a different equipment type per the contract, not b/c it's considered by the powers that be a step up.
More than likely, management just doesn't wanna pony up the $$$ for differences training AND replace an FO on the Q.....