What type of heater? Most heaters shouldn't get hot enough to melt the rubber. Still if you are going to use a heater you should have no problem using a metal or ceramic waterer. I use those rubber bowels myself in the winter and use no heater. They are easy enough to turn over and stomp to remover the ice when I change the water.
This is my first winter with chickens and I live on a wide open farm in NE Kansas so I was worried about frozen water. I bought this dog bowl from Amazon and though it hasn't been tested very hard yet, it is keeping the water from being frigid. I can feel a slightly warm bottom inside the bowl when I empty it and I've set it on a pallet to keep the girls from being able to fill it with hay as easily.