Well i have Asthma/Emphysema and i vape , negative things are coughing .So, i vape at lower temps because coughing hurts asthmatics .
If i'm using a Solo, i stay in the 4-5 range. On the Underdog, 11.4-.9 ish on a Pax -orange. Lower is better for me, but it may be different for your friend...