I would note that ereader-store.de currently doesn't advertise any 6" eReaders. AFAIK, the only stores stocking even the several-months-old C67 Carta 2 are
The Russian store and
Onyx-Boox's own TMall store. Retailer coverage of specific O-B devices is becoming increasingly spotty.
[Correction:
www.e-readerweb.nl also stocks the C67 Carta 2.]