Another low-time Instructor here, but you did ask for all comments
I think that it would be a nice "gimmick" to have when teaching some sequences (i.e. that the wing *really does* stall at a certain AoA, not IAS etc.). That in itself would be nice, but it isn't absolutely necessary. Showing the gliding attitude might be another where it is useful.
But as to the benefits to trained pilots, once the training is done there really isn't that much information that an AoA vane can give you that other stimulus can not. Light planes are pretty forgiving little things, on the whole, and so long as you fly the right attitude and power etc. then you shouldn't really need another instrument telling you what you can already feel through the seat of your pants.
Mind you, calling out an AoA check on short final would sure sound impressive!
grade_3