Skippydiesel, I note your concerns on filtering into the aircraft, rather than the foldable fuel bladders, and your reasoning is worthy of support, particularly for a low wing aircraft.
I have made a deliberate choice to do it my way for a few reasons. Firstly, my aircraft is a high wing, and managing a small stool, funnel, and flexible fuel bladder is a high-wire act fraught with incident (big spills onto plexiglas, inability to see when tank nears full, longer time pouring fuel, stumbles & fumbles at a windy, rainy, dusty, exposed outback aerodrome). Much easier and safer to funnel into a bladder at my feet, under shelter in a petrol station IMHO.
Are you saying you filter both into your fuel bladder, AND the aircraft? If so, have you considered the high volatility of Premium mogas? In a sealed container, the esters stay in solution, but slow pouring through a funnel (twice) would see a portion of these evaporate, lowering its effective RON. When I'm at home, I deliberately chose a petrol station with high turnover, on the assumption that their premium fuel is as fresh as I can get it, for the same RON reason.
My fuel bladders are new, and only ever used for my flying activities, so I have confidence in their integrity (I'm happy to hear otherwise). Being collapsible, and remaining sealed and flat, there is very little air within them for moisture to develop, I would think. Of course I always pre-flight including a bottom tank drain/inspection for water.
I do my annual maintenance with a LAME, and over the last 5 years, I can report that my fuel filter shows no adverse effects from my refuelling protocol. Long may that continue...
Dave