it's fixable through keepalive or session scope.
The demo uses keepAlive and the issue occurs as I described it.
I'm using Seam with conversation-scoped objects and the problem still occurs.
The problem seems to be that only hitting "next" and going to a new page seems to save the previous page. Perhaps this is some sort of caching issue?
I figured out the issue. The "previous" button has the "immediate" property set to "true" which obviously skips processing the form and therefore doesn't save the values.
Not sure if this was intended with this example, but as stated in the initial post, it causes the somewhat user-unfriendly behavior.