What a neat idea. I've only encountered this with sticker art, which is also a neat idea for trading and posting personal art in public but they aren't very likely to last long. How archival are these, do you know?
The paper is archival and they're specifically primed for painting, so I assume that they're pretty good. Oil paints alone are some of the longest lasting art materials. If the paper decides to rot away, the painting could still be applied to a new surface. They sell all kinds of sleeves and accessories for ACEOs too.