I downloaded the app on my old phone to have a play around with, and when I tried to export my database I was met with a pop-up containing a check box for "Keep the database encrypted". I assume you have to have first encrypted the database with a password before being offered this, so perhaps if you haven't added a password then your back ups will be in plain text.

I have to say it is a really nice app. Next time I'm changing phones I might make the switch.

You could always use an old phone stashed away somewhere, or even download an Android emulator on to your computer and install it on that.