I estimated at one point that my regulator by-passed a max of approx 8-9
gallon hour and that was at idle.  

===> Ed, Have you tried to estimate what happens when you turn the second
pump on?  Worst case would be landing, with the 2nd pump on, and engine
close to idle.  I'm assuming that most folks use the 2nd pump like you do
with the electric pump on a Lycoming.  In other words, do you turn both
pumps on for takeoff and landing?  

Cheers,
Rusty