I think that the claim that your engine is threatened is a bit much. I agree that if you have water and growies in the tanks, then you'll obviously be sorry because your filters will become jammed. The primary and secondary filter systems with a (for example) an iniital RACOR type filter followed by a very low micron engine filter should realy protect your injectors.

I think that a proper vent line (with a loop) and a vent outlet should really protect your tanks. Obviously if you get really pooped or discharge a hose in the vent.

The biggest problem is letting the tanks get gunky by not cycling the fuel. Using additivies and cycling the fuel should protect your fuel supply -- as long as you don't already have a problem. If you have a problem with water and gunk in the tanks, then this vent line descicant will do little to solve the problems.