The NEW red diaphragms, so far, have not failed in ethanol-diluted fuel. And, yes, they ARE pricey.

The black ones also seem to work well as long as the engine is started sufficiently often to keep fuel in the carburetor so the diaphragm stays wet.

Jon

Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify.
If you truly believe "one size fits all," try walking a mile in your spouse's shoes!
The Carburetor Shop