I think Ian is looking at adding expos to v5 of the setup. Here's how I have mine and why - all actuated by a three way switch:
Switch Up: No Expo, no limits. It's good to have a straight through mode, and you have to have one with all channels going to 100% or you can't turn the motors on/off.
Switch middle: -20 expo on AIL, ELE, RUD; RUD limited to 85%. This is my main flying mode: just a little expo to add some control sensitivity around zero, and yaw backed off a little from it's rather aggressive default.
Switch down: -50 expo on AIL, ELE, RUD; RUD limited to 65%. This is my "precision fling mode" - lot of expo and yaw limit to give me smooth, fine control. But, I let ELE and AIL still go to 100% even with all that expo: I really want to be able to dial-in an aggressive maneuver if I need to take evasive action!