What does your light say? Direction, quality and the motivation of the light are all much more important than the kind or brand of instrument you use. To get it right, use the light.
My friend, Will, likes to light portraits with one light. If given the choice I will always use two. I think the background usually benefits from its own source of illumination.
Three lights are generally too many for a single portrait. The more lights you use the more complicated production gets and it's almost always a case of diminishing returns.