This morning I duplicated the "First Scorchprint" Duel--Cast Iron vs. Aluminum on Gas" by bringing an 8-inch, tinned copper skillet into the mix. The pan in question was a Mazzetti rendered in 2mm (which pan they also do in 2.5mm, lined with silver).
As before, the parchment circle was cut to fit flat into the bottom of the pan and then was weighted down with tempered glass pie weight beads. The flame was precisely the same setting, "Low" on the knob-- but well above what I consider truly low. In any event, it was the same setting as the Ci and AL pans got earlier.
10 minutes later, no discoloration. At 12 minutes, there was a browning of the paper, but it could be seen only in contrast to other white parchment. At 14 minutes the browning was obvious. At 17 minutes, the parchment looked exactly as medium brown as the parchment in the AL pan had at 20:00--medium dark. I probably should have continued past this point, but I stopped because I didn't want to risk melting the tin lining with no real food in the pan. [Critics of my stopping at this point: Please continue with your own $$$ pan!]. Likewise, because of the lack of hotspotting, I saw no reason to run a "pre-heat" version for this pan.
Conclusions? Even though this copper pan was 1/2 the thickness of the Al pan, it showed the same evenness of heat throughout. It browned the parchment equally to that in the Al pan, but in 85% of the time--and therefore used 85% of the volume/cost of gas and was more responsive. But in both Cu and AL there were no hot spots, only even browning. This pan, at EU100 (n/incl shipping from Italy), cost double the price of the Al nonstick. $100 will buy a lot of 15%-margin better efficiencies, so I'm not going to claim the copper skillet was a clear winner in this test.
But on the other hand this test did not take into account extraneous factors like fond or the faster DOWNWARD heat responsiveness of copper...
I'll post the print when I get back to the house that has the camera software.