The PBY would be one of those additions like the P-47M and storch where Hitech tells Waffle to do it, and it shows up in a patch along side of something really sexy. In the MA they would be free kills for guys on their first day in the game. But, a small number of dedicated guys would find ways to be successful with them. For scenarios, they would still be free scooby snacks for fighters and even some bombers. And take forever to get anywhere. But, some one would still volunteer.
As for useful in the MA's kind of game play, the FW 189, J3 Cub, Po-2 and Lysander would be more useful supporting tanks against tanks.