Well for starters, the holydiver will sound much nicer than a Seymour duncan... :P
I don't know much about the SH-6 Distortion humbuckers, just that i'm pretty sure they have a pretty high output. Now the holydivers are fairly hot too, i think they give out about 16k output, which is quite similar to an SH-6 I think. Although this doesn't mean they sound similar.
To be honest, i can't really comment, as I have played Holydivers, but never SH-6 distortion pickups, although I should think Holydivers would sound considerably nicer... :D