As Doug said, other opinions will vary. Mine does. I personally think a fitted gun is far more enjoyable to use than one that doesn't fit and you have to compensate for the poor fit when you use the gun.

But a fitted gun only makes sense if you have a proper and consistent mount. If you do and if you like the AyA 16 ga then go for it! Amortize the thousand bucks over the years you expect to use the gun and it becomes trivial!

By the way, is the 16 ga AyA build on a 20 ga frame? Have you shot a 16 ga AyA?
The AyA #2 is a great shotgun I have a 20 ga that I use a lot and love. But I do not like the 12 ga. Big handling and feel difference. Make sure you try out a 16ga before you drop the nickel.