Bottom line, if you're contemplating a trip to IL in the next year (after Jan 13), LY is probably the way to go.
1) Your readers are far more anticipating an LY trip report than an AC TR
2) These LY fares are FULLY refundable (unless PL charges their own fee - Expedia doesn't AFAIK), while the AC fares have a 600 CAD refund penalty.