I experimented with printer paper, parchment paper, and watercolor paper with varying results. Note that if you use watercolor paper, the tooth of the paper prints through, giving extra texture.
I had interesting prints with stencils, as shown here:
The main drawback of fun foam is its porous nature. Although most of the paint may be cleaned off with a damp paper towel or alcohol, some of it remains and stains the plate. However if acrylic paint is used, after it dries it will not bleed onto later prints.