I have purchased one and it has been a whole lot of fun.

Just want to share a warning that you should be careful when playing with custom firmwares. https://thefirmwarehub.com for instance makes it super easy to flash the device straight from your web browser and try a bunch of new exciting stuff...

... however it also makes it extremely easy to brick your FM-1. Just mistakenly close the browser tab while firmware flashing is going on and poof, the poor thing is gone.

Apparently I managed to put it in a state where soft recovery (some key combination to put the device in re ouvert mode) is not available and it requires special hardware methods (the FM-1 Transporter method).

Not gonna lie, that is another kind of fun, and I got the hardware delivered today so I'll be at it soon, but in the meantime not much music was done.

Caveat emptor!