I don't think this is an attractive option for Canada. The main downside of EFTA is that you are required to follow a lot of single-market legislation, without getting any say in it.

Considering how tightly Canada is currently coupled to the US, this would be an absolute nightmare for many businesses. Yeah you'd gain a hypothetical overseas market, but in turn you're losing alignment with an absolutely massive market right next door! That's something like 60% of your import/export, gone.