I switched to mustache bars almost three years ago. I put on a shorter/steeper stem, and even added a "stem raiser" to get the bars higher. In accordance with prevailing wisdom, I set the outermost parts of the bars parallel to the ground. My hands would get a tad numb, and I attributed this to the angle of the bars. I recently did a major re-do of my bike (a Surly LHT), and, among other things, I tilted the bars up a bit. Perfect. The forward reach to the curves is now less, and the angle of the outer bars conforms to the angle of my palms. Think about it: Allow your hands to hang by your sides, and, keeping your arms relaxed, swing your hands frontwards. Note that the crosswise line of your palm is not parallel to the ground. I also moved the brake levers more to the outside of the curves. So far, I am quite happy with this decision.