Dunno about the sound in that configuration. I use them because it’s the sound I heard when I was but a callow yute, and, to me, flats on a P is just the right sound for a bass. Before about 1966, if you went to the music store and asked for bass strings they gave you flats. Then people started digging Entwistle’s sound with The Who (he played what are now Rotosound Swing Bass 66 roundwounds), and suddenly everybody had to have rounds. In those days I sat behind my Farfisa organ and listened to our bass player slam the dancers in the chest with the mighty tone from his Gibson EB0 strung with La Bellas and didn’t know from nuthin’ about guitars and such. Also, La Bella flats are super smooth and feel great to play. I usually play an hour a day at the least, and have barely any calluses on either hand. If I tried to play rounds now I’d be hurtin’ for certain! But if you switch to Jamerson’s gauge, be prepared for pretty high string tension. I’d imagine you’d be adjusting the truss rod to compensate, probably string height, pickup height and intonation too, and you might have a few days of acclimation, especially when playing frets 1-3 or so. From what I’ve read, Jamerson never did anything to the Funk Machine at all, and the neck was so bowed from the string tension that nobody else was able to play it but him. But man, what a sound!