Sure he has, although its only only guesswork on my part. He's very professional and good at what he does (== making money, isn't that what music is all about nowadays). I doubt Metallica wouldn't be as big as they are now had they never worked with Bob.

That being said, i don't exactly like the influence he has had on their sound over the years. Allthough its quite hard to say what comes from the band itself and what from the producer. And its almost impossible to try and think what would have happened with another producer..