I've always had SDs in guitars and basses I've played. But I scored a pair of Dimarzio 127s off eBay to give them a try in a non name Precision I've got. I had gigged the bass a couple of time just for fun but it lacked something - especially in the 4th string.
Loaded it with a Dimarzio 127 and boy is this a different beast now. Plenty of bottom end and a sort of thump none of my basses have. This is in the car for Saturdays's gig for a try with the band. Its a cheap bass, but this PU is great and makes it gigable. Two gigs with this and its paid for its self - now that's a result.
As a pro, I get paid for playing and sounding good - not for spending a wad on high end equipment.