Poor hot idle caused by ethanol gas? Whaddya think?

I have been using a product called Carb Defender in ethanol gas for many years. The hygroscopic nature of the ethanol, combined with the fact that left sitting any real length of time our vented carbs will allow the gas to evaporate faster than the ethanol, further concentrating the ethanol and attached H2O in the carb will really do a number on the small spaces (metering) of the carb and causes slowly worsening issues over time. In my understanding, Carb Defender attaches to the ethanol (yeah, I'm not a chemist) so it doesn't bind with the water. What I know is that my carbs using 10% ethanol on 4 old cars run really well and I have seen a bunch of carb horror stories without such measures. I started using it after Herb McCandles recommended it at one of his Carlisle workshops.

Back when almost all cars had carbs and vented gas systems, the gas companies put stabalizer in the gas, but with almost all gas cars having sealed systems they don't bother to do that because those cars don't need it.