If you have to connect on two airlines there is little chance of consistent savings. If the flights were from BOS, JFK, or Newark they would be filled with vacationers. Operating out of MIA will put a different type of traveler on the planes. If the times are correct maybe you will see some connecting to and from Europe. We are talking +/- 200 seats a week to start. You can easily fill that with working professionals doing business on both ends.