So deck landings. You want a stable airborne platform as possible to reduce your workload. Even if the ship is moving you want to stay stable relative to the world. Therefore ATT would seem the logical choice PROVIDED the system recognises pilot input. In this case SAS may be warranted but probably working against the trim (IE Force trim release not held down).
I would definitely recommend SAS rather than ATT for deck landings especially in difficult conditions. You can trim the aircraft to a decent hover before you move in but you want crisp control response to deal with the ship movement. On a flat calm day then ATT would work fine but for anything else I'd go for SAS - including at night.
The question was about the 412 and the ATT mode, while you can fly through it easily enough, isn't as good for any form of general handling as SAS mode.
For all the military-type training we did on the 412, ATT was only used for IFR - everything else, including SAR work, was in SAS mode.