Layering down and synthetics, as described by Patrick, is sometimes a great option. You can create a combo that is warm at winterlike temps, but still offers some of the security of a synthetic system. That is exactly what I frequently do, especially in summer alpine conditions.
But this combo, while flexible, is missing some features that a good belay type jacket will offer. An insulated and integrated hood offers excellent storm, wind and cold weather protection for your most critical piece of gear, your noggin. Also, you will likely sacrafice some storm protection, which could be critical if you are exposed to a long storm at near freezing temperatures. So I think the right option really depends on your likely conditions, and a combo synthetic/down layering system can be a good choice.