I'm using Jamerson Labellas on my S1 Jazz with wizard 84 pups, gives me twang or thump or something inbetween with good authority.
I'm 3/4 happy... but having issues with the E string. A google of 'labella E string' shows some others have had issues with QC. Its tone is different to the others and is a bugger to keep tune.... warm or cold enviroment will move it out, as will the warmth from the friction of playing for a while. Also, just the absolute slightest of movement on the tuner has an exaggerated effect. I'm going to have to try a more standard gauge which is a shame because I do like the 110's stiffness and epic girth, oooh errr. I also suspect my luthier filed the nut to fit the E, so I'll have to factor the cost of a new one into any strings replacement.
Flats, and also through bridge as opposed to through body stringing, have helped tame the bags of sustain the instrument had when it first came to me wearing factory rounds. I know sustain is a sign of a well put together instrument and that if you were a les paul, face melting solo rocking guitar type, your thinking would be different but I'm of the opinion that basses, mine at least, don't want too much sustain.