Damn it, Jim, I'm a doctor! Not judge, jury, and executioner!
Come to think of it, it's hard to imagine two more diametrically opposed characters.
...Well, almost. I just remembered that Urban's two characters in the Hercules/Xena
universe were Julius Caesar (a particularly evil version) and Cupid. So he has some experience playing polar opposites.
If they have him go the whole movie without ever taking off the helmet and showing his famous mug, that's a daring choice. I still think the Stallone movie could've made the helmet's removal work in a way that was truer to the character, if he'd been stripped of the helmet by force upon his arrest and was striving to get it (and his "good" name) back.