To transfer MIDI files from and to the QY100 I use the functions provided by the Data Filer program, in particular to move pieces of material to be assembled in phrases or to export small MIDI chunks to work on a DAW (or other sequencer).
Often, to "dump" a finished song I enslave the QY to the DAW (Reaper, in my case) and record all the MIDI at high bpm. Then in Reaper set all back to the right bpm and separtate tracks by MIDI channel.
I borrowed this from my workflow with the QY700, although there you can save a MIDI file on an USB thumbdrive, direct MIDI playback saves time, saves leaving half of the tracks empty for the "expand backing" job... and is more fun.
:)
prea