From what I have read, heated sidewalks are not efficient when the temperature gets really cold, as it does in Montreal. The average high/low in January are 1C/-5C in Oslo, compared to -4C/-14C in Montreal. It's a significant difference. The snow that melts on the sidewalks has to go somewhere. Some of it evaporates, but some of the melted snow can freeze again before it gets to the sewer.
Heated sidewalks are nice but if it hits -30 Celsius with the windchill the heat will be negated. Safer to use salt otherwise you risk creating a skating rink from the runoff.