I can't tell you about cancelled flights, but I just had a MPL - ORY flight this afternoon where they replaced a CRJ by an ATR, so the incoming aircraft took 30 minutes more to arrive at MPL, and then took 30 more minutes to go back to ORY, which adds up to about 1 hour of delay. That was notified by SMS yesterday evening, so I knew what to expect.
The bad part was that we had to disembark by paxbus at ORY
Appart from the delay, the flight was quite bumpy when climbing and landing (fun!), and the sky was clear so the view was amazing
I was not in a rush, so in the end I felt pretty happy about the change
