Okay...I'll take a stab at some "actual" differences....[Here's the disclaimer - THIS IS *MY* OPINION, ONLY - Worth What You Pay]

1. Immediate full torque available when moving off of center. Makes the "small" corrections faster for me to pick up, fix, and hopefully *hide*
2. Holding power - throughout the range, there is no fade...on my snaps and stall turns, for example, they LOCK and HOLD; permitting me a much more positive entry and exit
3. Resolution - I am able to very precisely trim, using the lower trim authority settings....for example, a single "click" at the low authority can be SEEN to move the surface. It's subtle, but can be important.
4. Mixes - because of 1 - 3 above, any mixes needed are more consistent, precise, and more effective.

[Reread my disclaimer!]