I did a weekend (5 dives) of diving in Lake Erie a few years ago. The first day I was in my Seaskin Nova with my Seaskin 250gsm undies. The water was 43F first dive, 44, and 48.
I was so warm that I changed to my 150 undies for the next day. Dives were 44F (at 147 feet) and 44F (at 127 feet). 49 minute dives, both times.
My head and hands were chilly. Otherwise, I was fine.
Depends. I wear a Arctic Halo 3D with my Seaskin in the mid to low 40's and I'm pretty damn cold by min 45. I can bear it until 60 or 70 min, but there's a point that I'm not enjoying it anymore. Now if it's a working dive (collecting / current) with the same setup I can stay in for longer in even colder temps. Down into the high 30's no problem.
I would put money on it you run a little hotter than most. Are you by chance the guy wearing shorts when short season is long past?