Put me down as neutral on this one. I don't specifically think there's a pressing need to allow all three; but (as long as entry quantities don't get out of control) I have no objection to it either.
One other thing to take into account is that I've often aimed to make sure at least two of the rules are Lix-friendly, but the third will often be only suitable for NL. Allowing all three might be a disadvantage to Lix players. Counter-argument: Lix entries are extremely rare nowdays anyway.
In favour, but I have a question. When we moved from one rule per contest to three, I was under the impression that this wasn't set in stone for all contests but whoever chose the rules would be at liberty to vary the format. Is this still the case?
Contest rules have always been able to, on a per-contest basis, override the general rules if desired. So I'm guessing this poll is more about deciding what the "normal" situation will be going forward.