Slings for sxs or o/u shotguns are often of the style with a noose that fits over the barrels, or in the case of many shotguns or rifle/shotgun combination guns, an attachment for a swivel is brazed to the sxs centre rib or o/u bottom barrel.

I don't know that I would trust a sling attached to a stud on the forend. A good jolt could overcome the forend latch allowing the sling to pull the forend free and the gun hitting the deck. Some shotguns just have the forend clipped on which required a pull on the nose of the forend to free it when dismantling the gun.

Problem with the noose type sling is that the bluing will be worn off over time where the sling wraps around the barrel.

I've often thought of putting a sling on my Miroku O/U gun but resisted the urge due to reason given above. I have a sling on my semi but is a plain light 1" sling with a sliding buckle. Slide to fully tighten the sling when shooting with the semi then loosen off for carrying. Hate slings flip flopping under the gun when shooting. Use the same sling on my rifles too for the same reason.