I have found out too late:
If anybody has tested the new gadget, please report it here.
WD MyBook firmware still has major bugs several years after launch, it's production has stopped and most probably it will remain as is...
WD MyCloud firmware, more than 5 months after launch, is very unstable. I have analyzed part of it and found pieces of shell scripts which look as written by monkeys.
Since the new 2bays version has the same CPU I'm pretty sure that it's firmware is very close to 1 drive MyCloud.
If anybody has tested the new gadget, please report it here.