We have gone from the MK to the GF for breakfast, and if you take the water taxis, you will get there a whole lot faster than taking the monorail. The monorail has to make 3 stops before you get around to the GF, which can take upwards to 15 minutes or more.
Everytime we have taken the water taxi, we have gotten there is less than a 5 minute trip. We really haven't had to wait for the water taxi, either... perhaps only 2-3 minutes while they disembarked, and then docked. The water taxi is very relaxing, and our DD loved it!