We at one time did have a dedicated server, but now just fly off of my physical computer as the host. Its really 6 one way, half a dozen the other. If you took two guys who with a dedicated server, each had a 40 ping, all in all thats really an 80 ping between the two pilots. As I host now, if that number is less than 80, then thats less lag and one less pipeline that you have to go through.
As far as "tweaks" go, we haven't made a single one. The one thing to realize is that if your computer struggles running "Lock:On" you will get lag spikes from the person who's computer doesn't handle it very well, and all people connected will also get lag. We've also found that the more complex the mission, (i.e. vehicles moving, other ai aircraft, etc.) the connection gets worse. So the moral of the story is, run as little as necessary for your mission if trying to fly formation.