I only tried that position once, it made me feel deathly ill with severe nausea. My most comfort+able and productive position is lying on the right side with my knees drawn up slightly. I also love a Castor oil pack warmed by a heating pad in the liver area. I stay very still and make little movies in my mind of the stones flowing out.
What is best for me may not be best for all. Experiment and see what is best for you.