My colleague tasted this feature last week flying back to YUL from DEN via YYZ. The 7:05am flight out of DEN was delayed but she was not worried as she had two hours to connect in YYZ. When she arrived to the gate to board her 2pm flight to YUL she was told by the gate agent she had been rebooked to the 8pm flight because the system thought she wouldn't make her connection! The flight was overbooked so there was no way to put her back in there. She was waitlisted for the subsequent flights with no success. She boarded at 8pm and the flight was delayed waiting for crew. She finally made it home at 11pm, 7 hours later than expected.