I wonder if this delay on the new site is costing them. Part of the excitement of NaNo is the big build up to it, with people posting new threads all over the board, many in preparation for their novels or to help other people prepare. But I think, by and large, people are afraid to post. I see a few new threads in some areas, but mostly I think people don't want to start new threads if they're going to be erased with the reboot.
But, I think that a lot of donating comes from exposure to the site. If you're seeing the "Store" and the "Donate" links there at the top of your forums, you're more likely to give in and buy or donate something. Goodness knows that that store link is enticing to me every time I go. But if people aren't spending loads of time on the forum because they don't believe there's a point to it at this time, are they losing out on the impulse buyers and donors? And maybe they're even going to lose participants due to the loss of October momentum.