Again you are asking a question that requires a quantitative understanding of general relativity and far more advanced math than I'm qualified to explain. The fact that general relativity cannot be quantitatively explained to a college freshman is arguably indication that it is not well understood at all (Richard Feinman would have said so, at least).

I do know that the computer inside a GPS unit *does* use that formula, however. I wish I could see the code that was used to program it!