If you die in a duel against a maul either you are have no idea how to fight them or the other guy was extremely skilled.
Simply put, in duels, using overheads as a mauler is a no-no. If you die from an overhead in a duel against a mauler, you are stupid.
There are 2 rules against fighting a mauler:
1) spam the shit out of him, and keep your distance. Mauls are slow as fuck, so you want him 99% of the time on defensive. Don't get too close to him, because you essentially increase his speed
2) Very few people know this but: NEVER EVER EVER EVER EVER EVER STAB AGAINST A MAUL. EVER. If you stab, it is 99% chance guaranteed that I can then retaliate with an overhead. It is the ONLY way I can give overheads swings against an enemy. Trying to stab a mauler is fucking stupid. Don't do that. Just forget you have stab when dueling a mauler.
edit: as for the OP, no. Mauls are fine. We can be powerful in groups and in small spaces. In duels we are pretty crappy compared to most other things. Basically, we are one (or two) trick ponies. Speciallized, if you will. And that is fine.
edit2: overheads as in "overhead while you are standing up". Dying from an overhead if you have fallen down doesn't count as stupid :3