If you look at the link previously posted, CS100 MTOW ("base") takeoff distance on a standard day is only 4000'.
The CS100 may not be able to do an MTOW takeoff on a very hot summer day on a 4000' runway, but neither can the Q400. There are so many solutions (route/flight/load planning) that'll make it work. So much stuff going on behind the scenes.
The company obviously isn't going to invest in a bunch of aircraft if they aren't going to meet expected requirements. Noise is a huge factor, performance is another. Bottom line - for landing or takeoff, it's all about the numbers. If Bombardier shows the numbers work, companies will buy the airplanes. Once the aircraft are on line, just like in any airline operation, if you get a bad RSC, you get iced up on the approach which makes the distance not work, it ends up being too hot at the planned weight to take off... if the numbers don't work, you don't land (or take off!!!)
YTZ is a really cool place to fly into, but in the end - it's just another airport that happens to have water at either end of the runway.