Has anyone used one of these?
Yep, I got mine second hand and like the form factor for my keyboard rig - just the right size next to my damper pedal. I like that it’s bus powered, and adds an expression pedal over USB, since my controller keyboard doesn’t have a separate expression input. I use two of the foot switches for simple next/previous , and the expression pedal for organise swell or synth filter control, depending on the song/rackspace.
In the 2 years I’ve been using it I’ve had only two complaints:
1- the USB port broke when someone stepped on the cord. I had to solder in a replacement port, which I concede is not something everyone will be comfortable doing, and
2- the expression pedal loosens over time. When loose it will throw many CC messages! Tighten with an Allen key every couple of months.
hope that helps