Interesting experiment Jim.
The modified burner gives you 20 minutes of run time vs. 7 minutes. That definitely makes it worth the effort to modify the burner. I just make a little Well out of Aluminum Foil.
Charlie, if your only using kitchen foil get yourself one of those heavy duty aluminium cooking trays for turkeys etc that you use once and throwaway from a BBQ outlet or supermarket the aluminium is a whole lot thicker.