Delirium its not a placebo, it really makes a difference in at very low speeds (and pilot dependent). Thats like saying torque is a placebo.
I've posted this before, I'll do it again.
1. Throttling down one engine to compensate for a missing wing, you can fly straight and level with this.
2. Great hammerheads, you can really squeeze every last bit of energy out of the plane and can reverse very quickly.
3. Immersion (AKAK quote).
4. Spin recovery.
5. Making great donuts on the runway.
6. Ability to roll the aircraft more quickly at the cost of energy.
7. Out of plane, last ditch efforts (cut one engine and roll it hard).
That said, I can guarantee that differential throttle controls get more Aces High pilots killed than any other control apparatus. Most of the time the offenders overcompensate or attempt to use it in a situation that requires E retention.
If you don't believe me, come into the TA and I'd be willing to show you why its use is widely over-rated.