I may not be of much help but I have been working with the Multi Player coding of dedicated servers and clients for the past 2 years. The furthest I got was 4 players connecting over the internet to a huge mass of land with some trees. The players were extremely jumpy and not smooth at all.

The dedicated server activated the no-send command on every object it created after it was created on all clients, I though this was speed things up, but it didn't. I was sending the players position ever 10 frames and it was jumpy.

The last thing I didn't have time to try was to send clients positions to the server every second or so, and have the server tell other clients the positions, and have the client smooth it out. Basically like chess, gliding players and turning them on the client. This could be an issue though if I need up to date syncing on all clients if they are fighting.

Oh and on a LAN, the movements were great with 4 players, unfortunately I am looking to support at least 300 on one server.

I am just waiting now to see if they implement something.