Touchdown. There was a rather informative discussion on this just recently. You will find that opinions differ here.
I personally feel that running 100:1 at 80:1 is the same as running a 50:1 oil at 40:1. The amount of oil in the gas is not what's important. It's the amount of oil left in the gas after combustion that counts. (I believe)
According to the people "in the know" the 100:1 oil has a higher flash point than 50:1. What this means is that the 100:1 requires more heat to "flash" which is why you can run it at that mixture. Anything richer than 100:1 and you are defeating the purpose of the oil and you might as well just drop to the 50:1.

Now, that being said, I mix my 100:1 at 93:1. LOL