I like the idea of 2 sides! We can call them "The Horde" and "The Fighters". If you like ganging up on 1 plane and fighting over the kill then you can fly on The Horde. If you enjoy fighting and killing everything red then you can fly on The Fighters! I expect the ratio of numbers to be somewhere in the 10 to 1 in favor of the Horde. Sounds like a TON of FUN to me!!!!!

This would be bad IMO.
2 countries would not work to improve play. I think "humans being humans" it would encourage "like minded folks" to gravitate to the same side. Imagine all the "good players or experienced, anti horde" ones on one side and all the lesser experienced, new and base takers on the other. One generally considered the "elite side" being less inviting to new folks and very "anti horde" and crammed full of "lone wolves". The other side clearly being more inviting to new folks and embracing a "work together attitude". This would create 'as experience increases" a natural exodus from one to the other and never the opposite.
This would be terrible and would guarantee stagnation.
The experienced side would have a field day, for a while. Until they got bored as hell, and they would get bored as hell.
The less experienced player would get discouraged or just gravitate to the other side, and without a reasonable switch time you would have the same problem as now.
I always thought there was one of 2 ways to improve the play for all.
#1 - bring the "base takers/new folks" up to the standard and experience of the more experienced. Ha we all no this is not possible as improvement comes in it's own good time.
#2 - Find some way to get the experienced to "buy in" enthusiastically to the 'WAR". This one is more possible imho. But the way bases are taken and how the "war" progresses now doesn't do this.
The 'war" needs to foment interest from the experienced 1st, then through they're excitement the others will follow and emulate.
Otherwise, reduce switch time to 1 hour and all will balance itself!
$.02
JUGgler