Slight correction there.
SkyService does have flights from Toronto, once a week (Thurs) during high season. They are called "Direct" flights, but in reality, there is a stop in Cancun on the way down. The flight home is direct.
It is great that we don't have to change planes or deal with Homeland security (ie USA customs).
I have used this service the last two trips and LOVE IT!
Hey they even had fantastic seat sales this year!
Hopefully they will offer the same service again next year.