Well, expo will soften the center area of the control sticks as little or as much as you want. It makes it easier to fly the plane smoothly. Simple.

For instance, if you have your low rate switch set for only 10% of available control throw, then you will probably have smooth control movements when you need to nudge the plane just a little. A nudge isn't much with only 10% of the throw available. But, if you switch to your high rate position and then have 100% control throws, it is nearly impossible to give any control a slight nudge to correct for minor flight changes. That little bit on low rates is now a whole lot on high rates.

Another reason to have expo is when you have 2 or 3 rates dialed into the radio. It is very nice to set the expos so that when you switch from low to medium the controls still feel the same until you really move them, say for aerobatic stuff. Expo will give you a seamless sort of feel when you switch rates so that you don't get any surprises.

Some people like twitchy planes and that's okay. Some people turn down the rates so that the plane is more docile and that's okay too, but they are missing what the plane could do with full throws.

I have a Widebody pattern plane and there is no way you could get much out of its potential without expo. The big rudder is very effective. I like that as long as it is effective when I want it to be. I would hate the plane if the rudder didn't have expo and was super sensitive all the time.

I hope you are getting something out of all this talk, Rook.