So my very first impressions:
It‘s very cool. I think I like it and will keep it. (The price was 265€ for B stock)
On the pro side we have:
* very handy and comfortable
* keybed is very good. The same as the reface models
* has lcd panel with clear text for voice names and functions
* has little built in speaker that is ok for hotel room
* works on batteries
* local sound engine is not bad. Has adjustable filter, reverb, chorus, DSP
* has USB connection and real midi in/out
* has bluetooth LE with small latency when connected to iOS
* line out is only mono, but headphone out is stereo and level is adjustable
* works perfectly on portable speaker (Marshall Kilburn or Bose S1 Pro)
On the negative side there are two surprises, however, theses documented in the reference manual, and they are described in the blog post of PJ:
* The is no organ sound. (It has a rotary speaker DSP program, but not sample to use it for)
* The Sustain Button sends no midi out message. The only CC sent is cc1 modulation. And pitch bend. Nothing else. No volume, no expression, no sustain, no nothing.
So when using it as midi controller to play sound on iOS device, it works well, but you cannot change volume, use sustain or toggle Leslie speed (except using mod wheel cc1 for this). IK Sample tank can map cc1 to Leslie speed. But Korg Module expects cc64 (sustain) which is not available.
Overall, it is very comparable to the Korg MicroKey Air 37. Keybeds are very similar, USB connection and bluetooth LE are equal. (MircoKey sends sustain message, but therefore you have to attach external sustain pedal, it has no sustain button.) But the form factor of the Sonogenic is much more fun. Did I say, that I like it?