I've never been wowed by Berstein, due to his conservative approach. I think the most should be done at once. Your basically giving up a percentage of your life (down time) in addition to the cost of HT. One pass max vs. 2 passes? No thanks. I'd agree w/ the 3500-3750. Honestly I'd go w/ HW or Rahal, as these Madevia/Dr. A, I've never seen their work. Also, that 30-35 cm2 would give a thin look, unless you have great hair characteristics (wavy, course, dense donor)