Today I mixed up a gal of 40:1 using 100LL avgas. Fired up the Jred and worked it for about 20 minutes. The results?
It is amazing how far the spark plug shot out of there! Missed me by inches... wow. Atleast it was a good story; fact is it worked well. Low setting is a touch rich, and I will turn it down eventually. Idle is smooth and steady. Revved up willingly, maybe better than on the other fuel. Avgas is lighter than auto gas, and will flow thru jets easier. Might richen things up a smirch. Power in the cut was maybe a tiny bit better, probably not worth the extra price.
However! watching the expressions on others when they see me pouring in the avgas will more than justify the expense. Now the genuine racing gas (110 octane) might be a benifit if the compression was increased and the timing advanced.