James, what thickness is the suit you are diving?
It's a 5mm Pinnacle w/Merino lining - it is a good bit warmer than other 5mm suits I've gone diving in. I'll bring a 5/3 hooded vest to go over it, but not sure I'll need/use it. I wasn't cold at all last time out w/just my 5mm suit, 5mm gloves, and boots w/2mm neoprene socks.