When the pipes froze, I had to cut a hole in the bottom of the vanity in order to assess the problem and where the pipes actually were. They don't come straight up from the concrete slab to the faucet; instead they come up about 2 feet to the right, raise up about 2 inches (or less) then run left to a point directly under the faucets and come up there. I know that's hard to picture. But unless I cut a hole in the bottom shelf, I would have figured they came straight up!
Some people are swearing by this new heat cord. And it sounds like it might be a little "neater" installation, which is important to me. I'm not sure that "just" foam pipe insulation will be enough to protect them from freezing. Oh well, I better make up my mind quickly or it will be spring before i know it!