I'm a guild master of a fairly large guild.
I do not believe this will be an issue. Not for a couple months.
See, there's a reason BW is controlling all of this. They are using their own calculations to figure this stuff out.
Of course, their formula could be badly wrong, but it's pretty safe to assume that the vast majority of people eligible to transfer will take advantage of it. I really don't think this will be an issue for at least a couple months, if at all. If you look at pages 2-3 I was a huge, huge skeptic ringing this guild splitting up bell. I'm now convinced this will simply not be the case.
Here's my issue with the whole "calculations" thing...Its already proven to not take into account the human reaction factor..and its more than once bit them in the rear end. Its doing it again. Mathematicians can't calculate the human factor. We're not calculations. We're fraking people.