There is no disadvantage in using the Visitor Toll Pass. You would pay the lowest toll rate and no extra fees. Only potential downside would be the hours of operation for the pick up counter (8 am to midnight daily). There is a drop box for returning the pass at the end of your trip.
You sign up online and there will be a pickup location near the rental car counters at MCO. Once you get into your rental car, you hang the Toll Pass from the rear view mirror. All tolls will be billed to the CC you entered at the lowest (electronic toll) rate approx. 3 days after you return the Toll Pass.
Loved it the last time we used it. Didn't take long to set up, was free,except for tolls and didn't have to stop at the toll booths.
On your way out to the cars, there is a booth for the pass. When you return there are bins to drop it in.