Yeah your worries seem to be the norm; but I have just not seen it in the fuel system...........yet, lol. Course my Eddies should have ethanol-compatible seats; as should the Magnums.
But I haven't had the heads off since 2004....... so IDK ................
The reason for post 27 was just for the OP to be fully informed. It was NOT to blast you or anyone else, cuz your American fuels seem to be more harsh than ours. Again IDK.
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Here's the the thing that steered me towards ethanol; Now I read this about 25 years ago, so cannot say whether it is true or not; so here goes;
the octane additives in non-ethanol gas, with each increase in rating, cause the fuel to burn slower. In my naivety, I thought to myself, why on Earth would I want a slow-burning fuel; give me the lightning gas, lol. And so, my engine was designed from the get-go, for ethanol 87E10. If we had say E15 or E20, for a competitive price, you bet I would experiment with it.
But I admit, I reduced the amount of rubber in my system to the bare minimum, and I add stabilizer for storage. The Holley that I now run, leaks it's primary bowl dry in a few days, so that's "covered", Lol. No, the Holley doesn't leak because of the fuel; one of the pump screw holes barely holds torque.