My experience last weekend:
YYZ-YXE Latitude Reward booked months ago and I eupgraded about a minute after booking the award. (E25 here). Checked in at T-24 and got Boarding Pass for 2A. About 3 hours later I get a text that my seat assignment has changed and that I am in 20D (Exit Row Aisle Seat) 7M8. When I got to the airport I politely inquired as to what went on. Was told "Operations made the call."
Next day I got an email from AC Marketing. $350 and 2500 Aeroplan points.
I took the deal