I can save CAD$400 on a YYZ-SDQ fare at Xmas with an ER3 via BOS (and return via MIA per usual with 4 hours to connect, e.g. the minimum) - I travel with a 21" roller and a computer case - how feasible is this flight with carry-on and what appears to be no J/F? (Do they do the "Valet" carry on stowage at the door of the plane?).

On the plus side it looks like a 777 to SDQ from BOS which would be spiffy.