Honestly you couldn't pay me enough to use the Seymour Duncan SPB-1, I had one and couldn't wait to get rid of it, LOTS of bass, no mids, not a great deal of treble.
If I was playing dub reggae I would have loved it but in a rock setting (and by rock I mean classic rock not heavy rock) I got absolutely buried, the SPB-2 on the other hand is a fantastic pickup, not a great deal of treble but lots of mids, decent bass, when I had one I used to run one without a tone pot and got a great sound from it.
Nowadays if I was looking at replacement pickups I would try and get one with as flat a response as possible and shape the tone with EQ but that's just my personal preference.