My Ip does not change, it's just my adsl sucks sometimes.
On the GPGnet times, in case of connection lost, the issue was not sure, so it was not good. But now with FAF, the issue is simple: if you disconnect you loose. It's good because it avoid cheaters to unplug their Internet cable when they see they are loosing. But it also means that 50 seconds after a opponent lost his connexion, there is a free win button which appear.
And I think it should be 120 seconds (for ladder games only).
I appear that players are more fair when playing custom games.