My go-to response for most metal players has been 'If you don't have a Miracle Man, get it. If you already have a Miracle Man, then go with ...' X, Y, or Z pup, depending on what the person is looking for.
I think that the MM is the best metal pickup out there, and if you're going to have only one BK, and you play metal, then that's the one to get -- it's a terrific, all-around pickup with a natural compression and lots of harmonic overtones.
The Holy Diver, by comparison, is a bit more vintage-sounding. I would compare the two by eras ... the Holy Diver is good for that Diver Down, Pyromania, or Bark at the Moon type of sound. The Miracle Man is good for that Back for the Attack, No Rest for the Wicked, or even Skid Row.
The Miracle Man will definitely work in a Les Paul type guitar without being overly bright. Many people have used MM in their Les Paul guitars.