I don't know whether or not they'd consider this change substantial enough to refund; but a 50 minute connection in CLT doesn't really allow any flexibility at all. I don't mind running for a connection, but it's a very long way from our arrival gate to our departure gate, and since the doors close ten minutes prior to departure, we really would only have 40 minutes. We'll see what they say, but as you suggest, I'm going to research all of our options before I call.