The ethanol is not what is causing the leaks; Rochester B's are quite capable of leaking any fluid which is placed in them

The ethanol WILL cause a neopreme accelerator pump to become hard and fail on vehicles engines which are only started occasionally.
Leather accelerator pumps (used before "buy it at the lowest cost at all cost became a fixture in this country") are impervious to the ethanol.
How often you will be required to replace a faulty accelerator pump depends on the pump material and how often you start the vehicle.
Jon.