I don't really see a problem with that. Out of nearly 650 flights in my life, the majority of which were on CO and since 2000, I can count the number of cancelled flights I've had on one hand. And none of those have required a reroute onto another carrier. I've had a few delays caused by maintenance, ATC, or weather that caused me to miss a connection, but again, nothing that's required a reroute on another carrier. I don't think the odds of a flight being cancelled, and a reroute on another carrier being required, are any greater when I've paid for a ticket in full with TravelBank dollars, or used what I had to pay for just a portion of the ticket.