As a data point:
I'm running 2 ML-level leagues. I did what Matt suggested and set service time to 0 and wait time to 10 years.
What I'm seeing is that while it will let people go onto either ballot (and sometimes, both), it's erasing the history if the player changes ballots. I.e. a player who gets, say 10% year 1, 12% year 2, 5% year 3 in league A loses that history if he's put on the ballot of League B. Year 4 of League A/Year 1 of League B, the player will only show the League B total.
So it theoretically allows you to catch everyone, but it's not going to be a complete history if you run a more-than-one-ML set-up. That's a bit of a bummer, and I wish it would be fixed. However, I am well aware that this is yet another case of "most people only play with one ML" so it's unlikely to happen anytime soon.
