A German martingale is going to teach him (and you) how to feel "head down with the aid of a gadget." It will unfortunately not show you "round" or have lasting effects past when you stop using it.
A bit with leverage action is going to have consequences when you have a Hulk moment.
My honest advice to you is to speak with a good gadgetless trainer - maybe even do some dressage - and really learn what light and round is. Once you have that, you have the world at your feet.
Posted via Mobile Device