I'm no axe/maul expert. But I've owned a lot of them, from the cheap box store axes/mauls all the way up to a few gransfor bruks mauls and axes.
I had one of those muellers for a little while. I didn't like it. Mine didn't have the over strike protector on it, but the same head.
90% of the wood I split is elm, so maybe I am biased. But it did not work very good for my needs, the deep cheeks only seemed to just help it get deeper in the wood and stuck more often. Seemed like I spent more time getting in unstuck then splitting.
I'm sure in other species of wood it wood be a good splitter.