I had a pair of Duncan SH1/59's in my Gibby Les Paul for a while and hated them!
I found they to be overly wooly and boomy in the bass, scooped mids and brittle sounding highs.
I replaced them 1st with a set of Seymour Duncan Seth Lovers, which I really liked, and then replaced those with a set of AIV Mules and couldn't be happier.