WOT
Ive heard what you described, thats why I was leaning to the gdp mechanical it still uses the factory pump to start and if it has loss of pressure I believe
Call Richard at GDP 509-993-4923, he will lead you in the right direction for what you want to accomplish.
The only con I can come up with applies to any of the systems that require a pickup tube... fuel slosh. I get around 1/8 tank and I drop to 0 PSI when I stop (fuel sloshes forward). When I put the pickup in it is within 1 quarters thickness from the bottom so I can only attribute it to the lack of decent baffles and no sump in the tank. Outside of that I like the FASS. I did do the vent kit, so even at 1/8th tank I put in 30 gallons.