Does anyone know what the recommended stick blender wattage or rpm is for soap making? I have been deciding between two models of the same brand; one that is 200 W with 2 settings (12,000 rpm or 17,000 rpm), and another which is 350 W with 2 settings (18,000 or 23,000). Some might say it doesn't matter and I'm looking too much into it, but maybe it does help to understand this and that it is a factor in soap quality, trace and the problem with the formation of bubbles. Thankyou for your advice.