I kind of think you would want to leave for the airport earlier than you are used to with Magical Express. Like 4-1/2 to 5 hours before your flight for clearing customs in Orlando.. On the regular transportation forum there is a thread with a bunch of reports of DME failing to get guests back to the airport in time to get to the gate before the first few boarding zones are called.
Since there is no resort baggage checking, it takes longer to load up at the resorts since all the bags have to go under the bus.
And since this is not a Disney exclusive, there may be more stops, say in the Hotel Plaza area (Disney Springs) or in the Sea World area.