Nero and I don't but we also have a significant amount of experience. Though I will probably start wearing a mouth guard when we duel. I have had one tooth broken by an Ultrasaber, I can't afford to relive that!
This being said I am an awful example to follow in this respect. Headgear and forearm guards should always be worn. Even by very experienced saber enthusiasts.
Cheers.
There you have it people, straight from a Master and I'm sure Master Nero would agree.
PROTECT YOURSELF! Dental work is not cheap.
Nothing would ruin your saber wielding experience like the loss of an eye of a shattered knuckle.