I like muzzle heavy. As noted if perfectly balanced, the muzzle tends to float up and down when aiming. Also, when I start my dive, if the gun is muzzle heavy it wants to point down, if the gun is neutral or muzzle light I find myself with one more thing to deal with in getting the gun pointed down.
Don't know if it's a big deal, but wouldn't a muzzle heavy gun also tend to have less muzzle flip?