If you've used other MIDI devices, even keyboards with a perfect "tracking" between note played and MIDI note being output, for inputting into music notation software, you know that timing issues generally center upon the capabilities of the notation software, as well as how clean the player is. There's usually cleanup involved when working on something which is intended for, say, publication.
Now, add to that situation any limitations and tracking issues of the G2M.
The Sonuus G2M v2 actually tracks pretty well. The original was a bit pokier.