400GH earns - ~0.39 BTC per day at current difficulty. In the 47 Days from 15 DEC to 28 JAN at TODAY'S difficulty you would make ~18.5 BTC
It should be safe to assume that by Mid December the difficulty should be up quite a bit more, I think 4 boards should be expected.
I agree I just thought I would cover the bases so on the miracle chance it ends up higher than someone doesn't say "D&T that liar he said we would guaranteed get 4 extra boards". I would bet money it end up being 4 boards shipped per original board for the MPP at least for Batch 1. Batch 2 & 3 well that might be a little different depending on when they actually ship.