MIDI is good if you're trying to change presets on multiple devices simulataneously.  If you're just trying to change presets on your H9, you can get an aux switch like the FS3X 3-Button Footswitch for less than a MIDI footswitch and it's easier to configure.  But if you're using an expression pedal with your H9, you might be better off just getting a MIDI footswitch, because although you can get a y cable and run both an expression pedal and a single button aux switch into an H9, you might want more than 1 footswitch.