I bought the big funnel because of the filtering capacity, (speed to fill, something like 4 - 5 gallons/minute). I've been using it for about 6 months, I'm not impressed. Every fillup I end up dumping about 4 ounces of fuel into my waste oil collector for recycling. There's a ring at the bottom of the filter that doesn't allow the last few ounces of fuel to get to the filter media.
I did test the filter with water, none made it thru the filter, so it does work as advertised. I also add conditioner to the tank before I refill and only buy my fuel from a busy truck stop, so I never had a problem with water before Mr Funnel.