Well blue...since the code to reduce the processing fee from GAT is no longer, and that fee brings it to 179, and the total in GD tix is 180, either way it will be less expensive than buying them after the change.
Were you planning on buying your child (b/c you and your spouse have APs, right, if I'm remembering it correctly?) an AP? If so, might as well just buy that voucher, instead of upgrading. If you're not upgrading, of course, that's a silly idea.