Although I have an Aerogold I have never used them for supplemental insurance. No real reason. Hadn't even occured to me. I did have problems collecting on baggage delay coverage on the card a few years back, so maybe that sticks in my mind.
This time out, I used PC Financial (Presidents Choice). They do the health insurance free for kids and it worked out considerably cheaper. I also am concerned about the limitations placed on cancellation for health reasons. Last winter my DD broke out with chickenpox a few days prior to a flight. When I called the insurer (don't know company-- booked by CAA) they said that it would only qualify if there was hospitalization. Fortunately, she had an incredibly mild case (had the vaccine) and they were gone in time for the trip, so it never was an issue. But, I was pretty concerned (freaked, actually). PC Financial has a similar provision, but when I called and spoke to a supervisor, she said that they always go by a physician's recommendation for children. Given that the odds are highest that a cancellation will come about because of non-critical health issues, this is the critical decision point for me.