It should be obvious that, if you have an exaggerated hips-back squatting style, your upper body has to lean forward to compensate and keep the weight centered over your foot. Simple physics dictate that (unless you are on a Smith machine) you will not be able to maintain an upright upper body position without falling on your butt.
If you are going to squat with the hips back and (consequently) a lot of upper body lean, then lowering the barbell on the torso will be a much more advantageous position for almost everyone (mobility permitting).
So, what if I CAN'T handle a low-bar position? The options, as I see them, are to develop a more upright (sit-down) position which may necessitate more hip and hamstring mobility work, or continue to sit back and strengthen the crap out of your posterior chain to compensate for the position of weakened leverage.