I’ve had 3 different sets of Flatwound strings on my Ibby.
First was a set of TI Jazz flats. Great strings, but the D string snapped after about 2 1/2 years.
I replaced them with a D’addario Chromes. They were on my bass for 10 years & but not changed them for the sake of a change.
I now have Rotosound 77 flats & they're still a little bright & zingy for my liking (almost roundwound sounding), so I’m hoping that they wear in, or I’ll go back to the Chromes.
Each set does sound very different & so far I’ve liked the Chromes the most. But the TI Jazz were very good too.