First off be careful. Futaba and JR/Spectrum are different of course. For less sensitivity I believe Futaba is - expo while JR is + expo.
Expo can be set to be more sensitive around center as well as less sensitive.
To find out how much expo you'll like you're going to have to play around a bit. I doubt you'll notice a difference below 30% expo. So start at 30 and go from there.
remember that if you're using double or triple rates on your throws you'll need more expo with more throw.
I don't recommend expo unless you're flying a big acrobatic airplane. I believe expo can be a crutch as well as a help.
I have expo set on my 35 and 40 % airplanes but I don't have any expo on my smaller airplanes.
Good luck