This is how teams will play out if let's say we have a population of 350 constant in a perfect situation with minimal guilds and low "guildless" pop:
Good guilds composing of 44.27% (155 players) of the server population
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- Guild 1 62
- Guild 2 37
- Guild 3 28
- Guild 4 16
- Guild 5 12
Evil guilds composing of 53.72% (188 players) of the server population
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- Guild 1 71
- Guild 2 39
- Guild 3 38
- Guild 4 22
- Guild 5 18
The remaining 2% of the population remains guildless
Essentially guilds 1-3 on both the evil and good team would have the force required to contest raid encounters and rare spawns, each side has one "zerg" guild with two other smaller guilds capable of doing the same feat.
Over time one guild from each side begins to press dominance and smaller guilds pool into the larger ones (guilds 4-5 combine to contribute to the raiding scene) now each side has 4 major guilds and this continue to fracture and pool into the zerg guilds until only 3 guilds remain on each side.
The largest and most powerful guilds compete within their faction to maintain dominance of being majordomo, the guild who calls the shots for their faction, it will be that guild who contests the opposing faction on raid encounters while the lower tier guilds begin to seclude themselves to casual raiding and pvp while the majordomo rakes in all the good and talented members and presses content.
By the end of the run only 1 guild from each faction will have the skill, numbers, and dedication to contest raid encounters and will control their factions economy, raid system, recruitment, camp rules, and rotations within the faction because there is no PvP recourse outside the opposing faction....
This leads to the smaller guilds and unguilded people to be completely stepped on in terms of camps, it allows them to be "ignored" if they breech the majordomo's "rule set" and will be subject to being prey'd upon by the opposing faction with no recourse by over half the server due to internal politics.
This is why FFA is a must, to end internal faction politics and majordomo style management of a faction