Main problem I see is this:
Just before the war is won, huge amounts of people switch sides to the winning team. The other day, it happened to be Bish. The war is won, perks divided, map reset. Upon login, the two teams who usually lost the last war immediately team up on the previous winner. I don't mind this at all, but what ends up happening is all the sticks who switched sides for the quick perks do not want to be teamed up on. They switched sides to be a part of a horde, and part of the 'winning' team. They now no longer have the ability to switch back to a side where they can win, so they log. This ends up with 120 Knights, 130 Rooks, and 67 Bishop after a reset.
Again, I'm not complaining, cheep 262s, you can get more perks in a single 38G or B17 run than you would waiting for the map to reset a second time, and there's no lack of targets. But then you get the 200 crowd complaining that the low #'s team is being poor losers, when in reality it's a few bad apples who are being Poor Winners (from the previous map).
I think a maximum number of switches per Day or per Map might be a better way of going as opposed to time based.