You are being offered a roughly 50%, not 33%, premium to accept a voucher over cash.
If you fly AC a good deal, this seems to be an easy yes. If you do not, you need to find out from AC what the terms are of the specific voucher being offered. E.g., can it be used on other *A carriers, code shares, other individuals, must the ticket originate in Canada, what happens to any amount remaining?
I would not rely on what happens with other vouchers.