I read these forums often, but never post... you guys are a lot smarter brewers than me.
I'll just throw this out there on the subject of 'suckback' though, so no one thinks that because their airlock is full after a 30 degree temperature drop, nothing got in.
As you cool the beer, no matter at what rate, you are going to suck oxygen in, and/or liquid in from your airlock. How much oxygen and/or liquid is solely dependent on the magnitude of the temperature change. The only other thing that can happen is a big pressure drop inside your fermenter if it's totally sealed, or in the case of plastic you might have it deform/collapse slightly. In either of those cases, you will have a rush of oxygen into your fermenter when you break the seal.
Whether that amount of oxygen, starsan, vodka, etc. getting in is ok, or whether it's better to keg, I'm not sure. Just wanted to make sure everyone understands what's going on (and if I was stating the obvious, I'm sorry).