I wouldn't even think twice about flying out of Buffalo, to me there is nothing worse then dragging the car seats, strollers, diaper bags and kids on the mile long walk in Toronto from where they let you off the plane to customs.
I love going over at Buffalo, customs in the car, the airport is so easy to navigate and they have a fisher price play area by the food court where the kids can play while you wait for your flights. The money you can save also helps.
I should let you know I live about an hour from the TO airport and 1.5 from Buffalo so I have to drive home either way.
allison