I had never flattened prints that way before, it works very well. I suspect that for 'good' prints one would want to protect the print from both the platen and the foam with some textureless material. Mat board?? I guess one also needs a "cold press" like a piece of metal or something to hold the print flat while it cools.
I did not paint the center part because the paint can indicated it was limited to 200F, however, in use the top surface does not get that hot. So I will go ahead and paint that part also.
PS: Jeff, I got an email from someone reading as follows "....maybe interested in parting with one of the [8x10] Horizontal Devere's..."
I can't post a picture on the PM, so I'm hijacking the thread to show it here. PM me if you have any interest.