There is NOTHING better than heated gloves for riding at temps in the 20s. For a short trip heavy, insulated gloves may keep you warm, but eventually the cold will seep through. And they are bulky, heavy, and make it harder to work with the controls.
Gerbings are thinner and lighter, more comfortable, and will continue to make heat no matter how long you ride. Highly recommended. Widder gloves also work very well, but are pretty bulky themselves.
To be fair, though, there is a downside: If the wiring fails, you're left with a thin pair of gloves that aren't going to do anything to keep your hands warm. On a long winter tour, I'd take either a second pair of gerbings or a regular pair of insulated gloves as backup.