I ran Sidewinder starting last winter. When I first got it I loved it. Excellent smoke, good power, stable tune. On my third gallon of it, my motor started ghost flaming during a series race. I was stumped. Tried a different gallon of fuel and the problem disappeared. Chalked it up to bad luck and bought a different gallon of Sidewinder. That gallon was fine. The next gallon, my ghost flameouts came back. Switched to a different fuel and the flameouts vanished again.
I've now switched to Byron's. I can't deal with the inconsistency in the Sidewinder, even though I love the fuel when I get a good gallon of it.
Your mileage and experience may vary.
P.S. After run is not required. I've run about 3 gallons of Sidewinder through two V-Specs with no after run and there's not a speck of rust to be found.