double duty wetsuit?

I already own a wetsuit that I use for paddling (NRS Ultra Jane 3.0 Terraprene). I signed up for the 2 Bridges Swim and I'm wondering whether it's a reasonable suit to swim in. I will not have the opportunity to try it out in open water before the swim, and I'm not sure whether trying it out in the pool will be a reasonable test (I'm concerned I'll overheat. It's very comfortable and stretchy). A few key descriptions below: 4-way-stretch PowerSpan panels that wrap from the tops of your shoulders to your belt line and along the sides adapt to your movements for unrestricted range of motion and improve fit. 3 mm Terraprene neoprene provides outstanding insulation in cold conditions. I'm not in it to win it, I'm a slow swimmer and this will be my first open water swim in cold water, though I do plan on rolling around in the water while kayaking the weekend before the swim. Thanks for any advice, Lyn