Will there be a sync of the read status of all messages? That is the feature that I need, the backlog is next to useless without me knowing where I stopped last time.
I can't think of much more that could happen. My opinion is: if you are a human equipped with a brain (which functions normally) there is not much risk using an paternoster.
Of course keyloggers etc. are a problem. But that is a different story. A bug which can be exploited just by grabbing any device might have a larger impact on the vendors reputation.
A keylogger, fake smc, whatsoever ist much more dangerous for a single person, because the attacker knows what he wants on the specific device.