Gripping with your thumb under the barrel/around your foregrip, I mean; I inferred that from how you described using your thumb to actuate a 3 o' clock light.
Short version: Having the weight of the forend on top of your hand is worse than having it in your hand for a fighting rifle. Skeletal support is great for standing comps, but for multiple targets and recoil mitigation, thumb over bore (or alternatively, running your thumb parallel but still above the boreline) is faster and better for transitioning and keeping impulse to a minimum. Rhodesians used it to great effect with FALs.
Before you dismiss it as a mallninja newfangled gimmick, give it a shot.
