I've had a guitar equipped with a Gibson 500T humbucker for years and I think it's my favourite pickup for really heavy stuff. It's a ridiculously high output humbucker - clean tones are virtually nonexistent if you don't turn the volume knob down - but it doesn't get muddy or flabby. One of the best pickups out there if you want to play thrash, death metal, stuff like that and you don't like active pickups.
I remember I used it to play classic heavy metal (Iron Maiden, Judas Priest) on the crunch channel of the Marshall TSL602 without any boosters. Those who had this amp know, that the crunch channel isn't exactly designed for heavy metal, yet with this pickup, the amp did fine.
5/5, a classic and I can honestly recommend it to anyone.