I have now fitted these strings to both my Uke Basses having tried all the black white and red other makes.. you know which ones if you are reading this.
These flatwound strings are the first that actually pitch correctly up and down the fretboard. The suit the sound I wanted as I play fender Jazz bass with flatwounds but on the Ukes, the sound it earthy, organic and punchy... all in one.
I have a Kala acoustic and a Mahalo solid body Uke which I play in a Celtic band. The sounds leaves the audience with dropped jaws, as the look for the hidden double bass, and I also use in rock bands and the solid bodly sounds remarkably similar to my "much heavier" fender jazz.
There is now no turning back from these. I can only recommend you try some.
Yes, they are pricey, but they last a heck of a long time. just keep them clean and wipe down after each gig.