Yogani said (and I find it's true) that a little goes a long way. an energetic nauli, where nothing much visibly moves, is all you really need, though yogis tend to go for the big showy effect.
On the other hand, I've been able to do big showy nauli since I was a kid (everything I learned easily in hatha as a kid I've been able to retain...we should all teach our kids asana!), so I'm not sure if you need to learn to do the big showy one in order to reduce it to an energetic one. In fact, I have no idea on that.