It depends on what their engines are rated at. The 700 series has better performance stats than the 800, so provided they aren't de-rated like Ryanair BHD-YYT (St. Johns), or even nearby Gander would be possible..winter time, with stronger winds might be a different story though!
It's unlikely, but if the City got Westjet it would be a massive 2 fingers up against Aldergrove!