On a recent tour in New England in 3 days of rain and cold, the gloves were soaked but the hands were warm. Warm is what I was after. I doubt that it's possible in those conditions to have both, even with 'waterproof' gloves. No more than it's possible to stay totally dry in the even the best rainwear. Rain, sweat, or both, depending on the material.

Most raingear does a lot better job just walking about than when cycling, which does stress the material and seams in ways not intended.

Mittens do seem be the preferred way to keep the hands warm in very cold weather. Makes sense.