Let me start by saying that I enjoy Frontlines and I do hope PVP becomes a constant focus of the dev team in the future.

Now, the flaw: players should not be separated by GC affiliation.

Reasons:
- it fragments perfectly functional communities (guilds aka free companies); what grand company I chose should in no way influence who I play with and vice-versa.
- it encourages migration of players from one GC to another in order to "be on the winning team"
- it holds no value in PVP (no different skills, nothing that actually says "I play TwinA because...")

Solution:
Get 72 ppl in and split them into 3 teams: the REDs, the BLUEs and the YELLOWs.

You want to go further? Split ppl into server groups and that way you can talk about some sort of "faction pride".

My 2 cents.