Hello Dick,
It is good to talk to you again.
I have tried the differential flap idea published by Palmer years ago. They did not work for me and the consensus of those that have tried the differential flap is that they do not work. Even Bob Palmer has since stated that if anything, the differential flap, if used should be connected to have the opposite differential than his article showed.
I have tried the larger outboard flap and will always incorporate some variation of that in my airplanes. They work. The consensus of many top flyers is that they work. Many of the top designs that have appeared in recent years show the larger outboard flap. This includes the Saturn and the Impact. There must be a reason.
I will not try to explain why they help, but they do. That is good enough for me to use them. It is one of those things, like on Bob Whitely's list of things that work: if the idea works, I do not need a technical explanation nor do I need to pay much attention to those who reach for reasons why the idea should not work.
Keith Trostle