For anyone interested there is a third party firmware now.
@darenager is this what youāre playing in your profile picture?
Yes 
I just sold mine a few months ago and was shocked to get an email notification on this thread, which had been dormant 10 years. I had the white one (no battery or audience-side lighting), but even with the custom firmware, it just received too little attention. Musically, itās cool, but too limited compared to modern grooveboxes. The primo model would still be good for stage, but upwards of $1000 USD to get one in good condition.
Fuck. Ten years 
Iāve got one of these sitting around in storage somewhere, had no idea they were going for that kind of price!
I got mine for 370ā¬. Almost in mint condition. So I must have been lucky?
Finally got one of these and I have to say, with the custom firmware by pikablue, this thing is like a whole different machine. I used the stock firmware for a day or so before upgrading and itās pretty incredible what theyāve accomplished. I figured his updates would be a few new bells and some QoL improvements like most custom firmwareās but this is the most comprehensive unofficial overhaul of a synth Iāve seen to date.
The flexibility you gain from all of the added layer types & routing options is almost overwhelming. For those unfamiliar, this custom firmware essentially adds parameter locking in a number of unique ways (timbre, filters, reverb send, vibrato, etc), up to 256 step length patterns, several new live performance modes that can all have internal midi data routed into them, hardware improvements, arpeggiators, and the list goes on. If you have a Tenori on in storage or collecting dust, I highly recommend giving this firmware a try.
I finally got around to putting together a video on the Tenori:On after getting it years ago. The difference with the PikaBlue firmware is night and day.
I wish Iād bought one of these back in the day!
Great stuff - good info and good sounds! Iām excited by the new firmware, I really wanted one when it came out but was turned off by the many limitations. Now it seems like itās finally ready!
Itās still weird and idiosyncratic and not necessarily to the standard youād expect from something released today (e.g. creating āsongsā is still limited), but it is now much more capable than itās ever been. Really cool to see how the community has kept it alive, and improved it.