There's no arguing comfort. I've been on dives with my 2mm shorty while someone else was wearing a 5mm full suit and a hood, and we were both quite comfortable.
Years ago in Hawaii, I did a night dive off a boat in my shorty with two other divers from Arizona, a newly married couple. On the way back in, I was thinking "ahhh, what a nice, warm Hawaiian night" then noticed the two Arizonans were shivering so hard their teeth were clattering. I took off my shorty and gave it to the wife to drape over her and cut down on the wind.
She was very grateful.