I've been diving the DC 200g jumpsuit with the 200g vest underneath it, with heavy polarfleece pants and a polarfleece turtleneck, and sometimes with a heated vest instead of the Thinsulate, and it's not warm enough. The DUI 400g is WAY warmer than the combination of all of the above, but it looks like I won't be able to use it because of the way it's cut in the back.