I don't think the cantilever will have any problems with an extra 4 oz in scope weight.
It's your gun and $$, but I couldn't justify the cost of a VX-R scope on a cantilevered barrel on a Rem 1100 slug gun. I have a cantilevered rifled barrel for my Rem 870. It came with a Simmons 3-9x which is as much scope as I ever see needing for a slug gun.