When I put an EMG 81 in the bridge position of my mahogany bodied guitar with a maple top, I thought it had such an extended treble response that it sounded like it was part single coil.
EMG 81's are the farthest thing from "dark" on my experience. They aren't quite as bright as the brightest pickups I've ever heard (Bill Lawrence XL's like Dimebag used), but they're bright.
They're actually not all that hot though. A lot of people think they are but they're really not. They're slightly hotter than medium output. They get the reputation of being hot mostly because people think "well metal players use them so they must be hot," even though, again they're really not. What's happening is that they are slightly compressed, and their low impedance output retains their brightness across long cable runs, and that extended, retained treble impacts the way amps feel and respond to playing, in a similar way to how a boost pedal might change the feel of an amp, so they feel hot, but they're not actually all that hot.