Well, earlier today I was playing on the server with around 75 people. I noticed large amounts of lag the entire time (as did {AW} and the rest, in a fight). Fighters were hard to hit *standing still*. I think 75 might be too much for the freelancer netcode, and I used to program client-server games, so I am not completely without knowledge as to game netcode.
A good way to test the server's limits, and this is what we did for Tribes: Vengeance (a game with notoriously bad netcode), is to set the server limit to something like 48 and begin increasing it in increments of 5 (then letting 5 people connect, of course). Keep doing this until you observe EVERYONES ping jumping up higher. When you notice this, drop down the player limit by 5, and you have a stable server.