I did a test burn on 4 of my stoves tonight. While it was by no means a scientific test, I think the results are significant. I also learned that the way I originally showed the use of the simmer ring was wrong. I had it upside down. When I started my test, I pretty well destroyed the simmer ring, so I'm gonna have to make a new one. Oh well...time for another Heineken!

That said, when the simmer ring is used correctly, it evidences practically NO discoloration at all. Lesson learned.
All tests were conducted using 3 tbsp (1.5 fl oz) of Yellow HEET. The only stove on which I used a pot of water was the stadium can stove since it does not require a pot stand - the pot is balanced directly on top of the stove. Since this is the way it would be used in the field, I figured it was a more accurate testing condition.
Stoves tested: Burn Time
Open well beverage can stove -- 10 minutes 12 seconds
Stadium can stove -- 10 minutes 51 seconds
Penny stove - no simmer ring -- 8 minutes 45 seconds (disappointing!)
Penny stove - with (crisped) simmer ring -- 23 minutes 45 seconds - impressive!
I started noticing that the simmer ring was heating up pretty good, so I snatched it off with my multi-tool and flipped it over and put it back on.