Dominance training is
not en vogue. Twenty years ago it was, and
positive reinforcement was a foreign concept in some circles. I'm not a fan of fads. My view is that it's best to err on the positive side, but an occasional dominance maneuver is not a terrible thing. There is no reason that you cannot mix and match positive reinforcement with dominance maneuvers - just be sure to use great care as you turn to dominating your dog - as a last resort, and only when you understand his/her character extremely well.
The most important thing to keep in mind is that dogs are profoundly sensitive creatures that pick up on the slightest gestures, cues, vibrations. Being alert and sensitive to their cues in turn is vital to becoming leaders they respect and adore and want to follow.
This pic by one of my favorite clients is entitled "mean-lookin softies". She uses positive reinforcement all the way, and she's definitely boss with her once-aggressive pit-lab mix.
First and foremost, being sensitive means paying attention to subtle body language. Theirs, ours, and that of the person passing by on the street. When we want to train a dog to follow specific commands, we tend to use sounds such as words and clicks. But when we want to communicate our general relationship to our dog, we use physical communication.