Hey Delek, just tested it and:
-it detects every MIDI IN device I've connected (sound card and usb keyboard)
-while the rec option is turned off, the keyboard plays great, with low latency (I don't know why the max. polyphony in the megadrive is three, shouldn't it be six?)
-while recording, even if it records three notes at a time, it just plays one "live"
This is a great new feature. Thanks for your work