Unfortunately, it isn't very stable at the moment:
Oct 02 13:50:15 shield amidiminder[355]: port removed shieldXL:MIDI in [129:0]
Oct 02 13:50:15 shield amidiminder[355]: disconnected shieldXL:MIDI in [129:0]-->Client-130:Virtual RawMIDI [130:0]
Oct 02 13:50:15 shield amidiminder[355]: port removed shieldXL:MIDI out [129:1]
Oct 02 13:50:15 shield amidiminder[355]: disconnected Client-130:Virtual RawMIDI [130:0]-->shieldXL:MIDI out [129:1]
Oct 02 13:50:15 shield systemd[1]: ttymidi0.service: Main process exited, code=killed, status=11/SEGV
Oct 02 13:50:15 shield systemd[1]: ttymidi0.service: Failed with result 'signal'.
Unfortunately, it isn't very stable at the moment: