We have the Transfer Flow 40 gallon/toolbox. Yes it is pricey compared to the gravity flow, but the price is long forgotten and this thing is nice. Over 720 miles with both tanks full. And just filled up in Va. where we go every 2 weeks at 3.54$ instead of here where it is 3.74-3.97$. The replacement tanks seemed way overpriced for the small increase in fuel capacity. I don't worry about bed space as we travel light and I have a utility trailer for hauling the mower, lumber, etc.
The way the automatic transfer works is to keep the ratio the same in both tanks and as they run low they will almost be the same.
To me, stopping where and when I want is worth the price. Saving on fuel is a nice bonus.
