header tank
I agree, the Header tank is well worth the money. Without one, you have the last 2-3 ozs of fuel that can be accompanied with bubbles as the engine sips them from the large tank. With the header, which is usually 2oz and rather narrow, there is practically no chance of getting air into the fuel flow. You get to use ALL of your main tank with no problem and the header is a more high resolution fuel gage for that last 2 ozs.
Sure, I use the fuel in my header tank, but it is now 5 minutes later than I use to end my flight.
Also, there are many people that swear by them religiously as a consistent source of fuel for their venturi carburetors. Jet jockeys love them for that reason because "Dead Sticks" or "Flame Outs" are just as dangerous as "Sudden Autos". We use them at work on our UAVs (Unmanned Aerial Vehicles) that have venturi carbs.
The Great Pumpkin