Doesn't FedEx and Purolator still run during the postal strike? At least that is what I've always been under the impression of, since they run independently of the CUPW? Shipping rates with FedEx and Purolator are usually about the same (sometimes even cheaper) as Canada Post anyways, especially if you are shipping out of country.
(but from the sounds of it Harper just pushed the back to work legislation yesterday.. so postal workers may be back to work soon)
Normally it's more expensive, plus with more Canada post locations, it's less of a hassle to get to. Sure a courier will take it to your door, but if you're not there it can be a chore to get to