Anyways, we started on Friday working on this move (of course weeks of prep work ahead of time) and things were looking good - we figured just a few minutes of downtime per database, everything going smoothly. Basically: shut down at old site, start up at new site. Almost no downtime at all. What part is screwing us? The standard files. We have over 30 million user-uploaded images, and keeping them in sync between two locations is turning out to be monstrously painful. None of the standard tools, or even the non-standard ones, seem to be cutting it.
Anyways... I'm very very tired, since Friday morning I've worked approximately 45 hours... if my math is right. I think so. Who knows. Yay!
So to sum it up in one word: despair.