The main difference is that BBFF understands your BeatBuddy project. It knows the song names, assigned drum kit (by name), the tempo, as well as how many sections each song has.
This is a failing of Midi Designer and even the MIDI maestro (or any software where you have to send MIDI commands). While each of those can send a MIDI command to go to section 3, they don’t know if there is a section three for the specifically loaded song, BBFF does.
While each of those can send a command to switch to drum kit #5, only BBFF knows that for your project, drum kit #5 is actually the Rock kit.
BBFF eliminates the need for mental hurdles and lets you see and interact with your BeatBuddy from your phone.