Out 12 trips with GCT/OAT, we have had to cancel twice,at the last minute, based on doctors recommendations. We did not take insurance on the first couple of trips, since they were last minute type trips, (and we were younger at the time) and did not not have to cancel on them, but assuming that we took insuarnce on 10 trips, at a cost of about a 10% premium, we would have paid for 1 extra trip, having cancelled and collected twice, we are ahead of the game by 1 trip. This is assuming that all of the trips would have cost approximately the same. Of course there would have been the other option, if we were ununsured, of taking the trip against the doctors' icommendations, which could have been far more expensive if something went wrong.
We have used Tripmate from GCT, but are not saying that this is the best buy, in fact, it is one of the most expensive, but the cancel for any reason clause is not available from everyone.
To determine whether you should buy insurance or not, you have to weigh the chances that you will need it based on your medical condition and the lead time for the trip. The longer the lead time, the greater the chance that conditions will change, You should at least have insurance against a catastophic loss, such as medical evacuation from a place such as sub-Saharan Africa or Antarica.