YYZ used to have 6 hour MAXIMUM transit time limit to use the automated transit passport check. If your transit is more than 6 hours you have to clear Canadian immigration and then you can do whatever you want - go to the downtown area or hangout at the airport landslide until 6 hours prior to departure. I am not sure, if they still have this rule though.
I have a question on this (unrelated to this deal) I have a red-eye from YVR to YYZ with a 12 hour layover continuing to Europe later that day. Are you suggesting I won't be able to go in and enjoy the lounge for those 12 hours (was planning on working all day)?