I purchased the Reactor Gloves 1 year ago in Size: Medium. They are great in air temps above 45, but at that point, it was nearly as comfortable to just take the gloves off. In 50 degree water and air temp in the high 20's, my fingers were very cold to the point of being painful.
I tried sizing up as I thought perhaps the glove was too tight, but it wasn't an improvement. I do use the gloves for washing the cars in the winter-time, though. The extra motion seems to provide enough blood-flow to stay warm.
I just received a set of NRS Toaster Mitts, though I haven't had a chance to try them out yet.