Have any you used both copper plates (like @Joel W. 's) and steel plates? If so, any difference in efficacy? Copper is well known to be one of the best thermal conductors (aside from silver) but I will have too wait on getting my hands on some sick cuni plates due to Joel W's current situation.
It is shame @Joel W. I finally built up the courage to order a couple of your plates after lurking on here a while. Maybe you should consider kickstarter or something similar to finance the equipment you need to start up again some day. I would definitely invest. In any case, I wish you the best...