When they introduced the Signature Plus and got rid of the previous no-blackout-date AP (premium?), I believe that the Signature Plus cost more than the old AP, but they were the closest comparison in terms of benefits, so people who had already purchased vouchers for the ?premium? AP got the Signature Plus without having to pay the difference. If you purchase a voucher for a pass that no longer exists when you go to activate, and the closest equivalent costs more, I don't think they'll make you pay the difference. If they do, they would have to also offer you the option of a refund since you never agreed to the higher price. If things change so radically that there isn't really an equivalent pass anymore, I think they'd have to go ahead and keep issuing the old passes to those who already purchased vouchers.