Don't know about the hair laser but as far as the full cap and sweating goes I usually try to wear a bandana because when you work up a really good sweat the hair around the edges will get soaked while the rest stays dry. I haven't really tested this but it could potentially look odd and might accentuate any lines a the edge of the base. I throw a bandana on tied like a headband just so I don't have to think about it.