I have no experience with kontronik speed controllers, but depending on the make, some kick in on the throttle much later and more abruptly than others (mostly becuase many are designed for airplanes and not helicopters). This is why many helicopter specific speed controllers have a soft or slow start option, to avoid damage. My Align ESC on my X400 spools up nice and slow, but the Jeti 40-3P on my Eco-8 doesn't "start" untill near mid stick, and when it does start, it's very abrupt, so much so that I usually spin my rotors beforehand to ease the strain on the gears. I've never stripped a tooth, even from a stand still as the eco-8 gears are pretty robust, but why take the chance.

I've just now looked up the specs on the Jazz ESC and it has lots of programmable features (really nice ESC by the looks of it ). Make sure you've got soft-start enabled. Also as stated, make sure you don't have a wierd throttle curve if you're using the governor on the ESC or it'll mess with your setup.