I really like the Holydivers I have in "Slash" - a McCarty Rosewood. Here's what I've found
Sustain - depends on the guitar in my experience, not the pickup
Harmonics - great for pinched harmonics, they come easy to me and I'm not a metal guy. More rock/hard rock.
Crunch - Quite a full sound, nice and punchy. Cleans up nicely with the volume pot, but still says quite fat.
Cleans - As crunch really. A fat clean sound, but nice and useable. Not ideal for blues styles for example, but certainly very useable. Not quite enough highs to give you that sparkle you get from a lower output pickup.
Palm muting - Like I said, I'm no metal guy and I usually suffer from "boomy bass" on palm mutes due to way I play. The Holydivers keep things pretty tight, and really good sounding. We play All My Life by the Foos and Holy Diver by Dio and they chug away nicely with a full yet tight tone.
Split - Slightly more P90-ish than Strat on the splits, nice and chunky. I use the bridge split for Wanted Dead Or Alive and Crazy Bitch - it works great!
Overall - they're quite a thick sounding pickup but with a nice clear top end to give some cut. Think of a McDonalds milkshake with extra ice ;)
"Slash" is the guitar on the left...
