My only concern with ties is one I've dealt with in the comm I moderate and comms in which I participate. I've seen it done before where if, for example, two things are tied for second, there's a tie-breaker and whoever wins gets second place - but the "loser" for that tie doesn't place at all then. I think it's only fair, if two are tied for second, that the loser of that tiebreaker gets bumped down to third place, rather than just not getting anything at all. I don't know how this or most comms do it, but in mine I do what's indicated above; a total-vote scoring rather than just breaking a placement tie and the unlucky tie-loser not placing at all.

But when it all comes down to it, as the host of the comm and challenges I think you should get more say than most participants how everything works, since you do most of the work involved.