RE: Anyone use a header tank??
PrivatePilot - I've thought about exactly what you're talking about, but in practice I've never had a problem with the fuel feed drying up during or immediately after vertical diving maneuvers.
A header tank is just one more thing that can go wrong in the fuel system. What I would do if you're really concerned about it is to make provisions to install a header tank, but try it without at first. Then if you do need it you won't need to perform surgery later, but if you don't need it then you've saved yourself a little trouble and avoided having other problems potentially.