Scott,
It is good to have water available when needed. I don't have that luxury. My creek is barely flowing. I couldn't pump more than 5 minutes right now before pumping my creek pothole dry.
I don't think you would gain anything in winter by pumping to the deep areas of your pond. There should be oxygen there now, and the water might be warmer than the surface. From what I have read, there are no benefits to circulating deep water in the winter, and it might even be detrimental if the circulation caused the deep layers to become colder. Better to pump onto the surface in the winter.