Expo will soften up your idle to 1/4 + throttle... but ultimately from 1/3 or 1/2 + you will still be hyper sensitive. It depends what your ultimate goal is. You would get closer to a true response by leaving the arms the same length and adjusting both end points and using just a touch of expo.

The only way to get a true throttle curve with an accurate response to get full resolution.

I always try to get atleast 100 / 100 on my end points for throttle and might use 5-10 expo at best but usually its not needed at that point. Sometimes a little bit does help though...