I noticed that LO(T) doesn't seem to be that cheap when it comes to YQ. I priced out a single one-way Y itinerary MXP-YYZ:
AC (direct): $195.50
LO (via WA): $160.20
Obviously the extra segment makes a difference for the LO itinerary, but even a WAW-YYZ ticket has a carrier surcharge of $78 one way. Perhaps not such a great deal after all...