I know this thread is several months old already.
I too had been wondering if there is a company that is producing any quality petcocks that would hold up under todays fuels.
I had purchased a petcock when I was restoring My 57 125cc Hummer. It lasted maybe several months. I had not used any E fuel through it at all. I am able to purchase premium unleaded without that E-Crap in it. About 40 cent a gallon fine on the stuff but that's just a privilege fee.