I still think it's a big difference between trusting existing OS'es and apps, which are under scrutiny by hundreds of security researchers and thousands of security nerds all the time, and willingly sending away all your data to a party who promises they will treat it well (I know it doesn't work like this in this case, but just for the sake of argument).

In essence, what you're doing is training an assistant to learn all of your details of your life and habits and the question is if that "assistant" is really secure forever. Taken to the extreme, the assistant becomes a sort of "backup" of yourself. But yeah it's an individual decision with the pro's and con's of this.