definitely do not do it!! I split wood with a metal handled monster maul for a couple/few years in my early twenties, but once my frontal lobe finally fully developed around age 25 I realized that I was an idiot and never picked it up again. here are the reasons
1. Shock - big time
2. The handle WILL eventually bend - and then the blade doesn't hit the wood square, killing your efficiency (even more)
3. Totally unable to index the head because the handle is round - this may actually be the biggest negative. I can't tell you how many million times I put all my strength into a swing just to have the side of the head smack the top of the round of wood - and THAT is some SERIOUS shock!!!!
Wood handles on tools are definitely always best.
additionally, the monster maul definitely did not split wood any better than a regular 8lb maul - and actually probably worse - and much harder on your body. I guess I just needed to feel like I was doing something extra manly or something - again, the frontal lobe issue.