I was in Montreal for New Years Eve this past year and even though some agencies were open, the pickings were slim. I also noticed several hotels had beefed up their security. For example, at the hotel i stayed at, i checked in on the 30th and was asked by the front desk to give them a list of names of people who might be visiting me on the 31st. They told me that they didn't want any partying and that security would be beefed up.
I only had a few buddies come over, since like i said, many of the agencies were closed and those that were open only had one or two girls working. Plus, that whole beefed up security thing. What they did at my hotel was cordon off the section leading to the elevators and when you'd approach that section, they had two security people asking you your name and your room number, etc. Similar to what they have going on at the Sheraton on weekends (evening and night).
So the bottom line is that if you're planning to see escorts during New Years Eve or New Year's, it's possible, but you might need a bit of luck and hope she can get through security if your hotel has beefed it up during your stay. Things appeared to be back to normal and it was business as usual on the 2nd.
Would i go back to Montreal on New Year's Eve? Probably not.