Where is it that you guys are getting that the ASHBM weighs more than a NMFBM??? From everything I've read, the ASHBM is lighter by 3-7 ounces (26-27 oz vs. 30-33 oz).
What I think that everyone here is missing is that since NMFBM is heavier overall and is a bit longer and taller, it means it has a center of mass located further down the blade away from the handle. If for no other reason, given the same distance traveled under the same acceleration, the NMFBM will hit harder. I think this gives it the winning edge as a chopper (pun intended). Not to mention the extra leverage that the offset fusion handle gives when chopping.
Now if I'm wrong about which is heavier, that would certainly change my guess.