I think javacontour is spot on. The alcohol in E10 will absorb a certain amount of water before phase separation occurs. These products might increase the amount of water absorbed by a very tiny fraction. According to a discussion I had with a tech at Stabil a few years ago, no product can completely prevent phase separation.
Plus, would you really want to send all that emulsified water through your fuel injectors? When I studied fuel additives for my workplace John Deere tractors, the literature implied there were 2 kinds of water "handling". One type would emulsify the water and send it through the injectors to be burned - bad according to JD. The other type would cause the water to be pulled out and settle in the fuel filter to be drained out manually. Maybe gasoline injectors are different, but still it seems bad to send a lot of crap through them.