I bought an OP-1 and it is the best product I've ever used. However, I was wildly disappointed to find the MIDI control input doesn't work with ALSA sequencer consistently (I need this functionality for a programming side project). I submited a support request, but it's kind of frustrating that I don't have the capability to just fix the firmware myself.
(Specifically aseqdump only works after restarting the computer and RtMidi qmidiin doesn't print anything and also prevents aseqdump from working if called..., if anyone knows why I'd love to understand)