I only have one real complaint with zone; Team Killing and just people hindering their team on purpose in general.
Of course, you can't SHOOT an ally, but explosions will kill anyone. Several times I found that a team lost due to the fact that one person switched and killed allies with a mortor or grenades.
The problem is that if you don't have grenades or explosives, you can't fight the team killers. They can attack you, but you can't fight back.
And a real annoying problem is when you use money to put mines around a base, and someone again switches to your team and throws a grenade into your mines, then switches back, just to hinder you.
That sort of thing bothers me a bit.
I think I know how to stop the Team Killing, however. The game already knows if you kill an ally with the "What a mess" message. I suggest that if you kill a lot of allies, the game either gives you a penalty or bans you for a certain amount of time.
So, that is my only complaint, really. Team abuse. Other then that, I love the server.
