at only 10 gauge you would have to spam it on cd, because it would then be almost twice as effective as fell cleave. Don't forget it's an ogcd and fell cleave is a gcd and by being a gcd skill it has the hidden cost of whatever gcd it replaced attached to it, whichg ranges from "only" 200 potency (heavy swing) to 380 potency + 20 gauge ( storm's path).