I would join FDD in my opinion.
I use M92 out of the box, no fixes. I use it for reading pdf and scribbling in it. It works to my expectation. The calibration of stylus is not perfect, but for underlaining the text and writing notes to text it is, to my opinion, fully satisfactory.
I see a big potential in this piece hardware. Some inperfections will solve the producer and the rest the users....