I think the best thing about the board is the fact that its movable. I've got one and have had great success avoiding the warping by just following the simple storage instructions (I think a lot of this has to do with where you live and how much moisture is in the air). When I'm done with construction for the time being, I simply set the board (and currently pinned plane parts) on its side move the it out of the way. This way I don't loose the use of the desk for other building tasks. This may work with a ceiling tile, but I'm not sure the tile will hold its shape after a week or so of not being supported by a flat surface.

Food for thought.