Looking for suggestions on values for dual rate and expo

[RightFly]

I am currently flying a 3ch Flyzone FlyLite. By the way, it is a great plane - like a Champ on steroids with its 30" ws.

I am planning on getting back to my 4ch Flyzone SkyFlyMax that is a lot quicker than the 3ch flylite so I am expermenting with expo. Have not used it before. Tonight I flew the Flylite with dual rates at High of 90% with expo at -15%. I used Low rate of 75% with expo at -5%.

I used the -15%/-5% as my Futaba 7c manual uses those numbers in the programing example. I realize some tech writer probably grabbed numbers out of the air, but I used them as a starting point. I really couldn't see a difference with the added expo values I used.

Is there a rule of thumb somewhere suggesting values? Or any suggestions. I would think less expo should be used for a slow flyer and more on the quicker planes.

Appreciate any thoughts and suggestions.