I believe when it signed off, CFCF 600 Montreal ran 10,000 watts by day and 5000 watts at night. Will 600 still have the same power? Will the new station be able to claim it is "Canada's First Station" as CFCF liked to say? OK, it's not really the same station, although the station that became CFCF was not originally on 600 and had the call sign XWA.
And the original 850 CKVL ran 50,000 watts nights and 10,000 watts by day. Again, will that remain?
I believe 940 is slightly nulled to the southwest to protect 940 XEQ Mexico City. Not sure if that's at all times or just nights. 940 was originally considered a Class I-B station. 690 was Class I-A with a non-directional antenna.
With a city the size of Montreal, it would make sense for it to have two English Talk stations (CJAD and 600) and two in French (CHMP and 940) as well as two Sports stations (English 690 and French 850). Vancouver has two Sports stations, although it has only one Talk station. Toronto has two Talk stations and two Sports stations.