I think simply using a simulator would work for standard stationary duels and that's about it. The action duel like duels, I've just been calling them hunt duels in my head, they are majorly effected by RP and movement around a location, so can't really be resolved in a simulator. If the players in character RP in the sim chat it's kind of functional, but there isn't really time for stuff like GM intervention when necessary, and I'd still rather see the duel in prose in the end. It's a bunch of trade offs really.