RE: 575lbs squat @ 158.5
I dunno - I reckon I squat a little wider than that.
So far as I know, the narrow stance does allow you to incorporate the quads more, but as the quads aren't the primary movers in the squat, this doesn't do much for you. The wide stance shifts the emphasis onto the hamstrings and the glutes, allowing you to incorporate a more powerful range of muscles into the lift and maintain a massive amount of musclur tension in the hole, provided that you are flexible enough to reach depth. I do believe that this outweighs the mechanical disadvantage the wide stance causes. The other benefit of the wide stance is obviously the reduced ROM. The narrow also forces the squatter to push their glutes much farther behind the bar, making it more difficult to stay upright and maintain optimum torso position.
In short, wide stance good, narrow stance bad...
...the exception to this (according to an article written by Brent Mikesell) is for heavyweight lifters with large quads who can rest their belt on their quads and their abs on the belt, "giving them a launching pad to blast out of the hole and stay upright" if they use the narrow stance.