So reporting back here. I just installed the TI Jazz flats and think they are a step in the right direction away from the rounds I had been using (for this particular bass - I am still a rounds guy generally speaking).
Obviously it will take time to have them settle. I was surprised by two things. The first is how bright they are on day one. I guess considering Steve Harris and his perpetually new flats that O shouldn't be. The second is how significant the adjustment is for the tactile difference. If playing rounds is like running on a outdoor track, playing flats is like skating on a sheet of new ice. It feels a little out of control, like you can't pre-load the strings with as much tension before playing the note.
I will report again when they settle down and I start to acclimate.