I shoot one. I would never buy a 56mm objective based on the size of the objective alone. I wanted a 32 power scope with target turrets so I had to deal with the larger objective. I personally like my scope to be as close to the bore as possible.
If you go to the 56, you need to consider your final sight height. Ballistic ally not that big of a deal, but getting a consistent cheek weld is difficult when you get over two inches. If you have an adjustable stock with vertical adjustment it is an easy fix. But certainly something you need to consider.
I run a 50mm and my sight height is 1.885" and that is as high as I would go with a non adjustable stock.