Gens Ace batteries, why the low C ratings.

[mattr]

Looking at buying a few gens ace batteries, and was a bit off put by the low quoted C ratings.
I know they claim that this is down to the correct measurement of the discharge (no fudging the figures!) but was wondering how far you can actually push them? i.e. What's the fastest/daftest motor and ESC you've run, and which gens ace battery/rating did you run it off?

I'm hoping for tales of insane 3.5 turn motors boosted to hell and back...........