Thanks to the fine folks at TalkBass I just put my first set of flats – the LaBella Deep Talkin' – on my '70 P bass. Dang, so smooth! They may not have the same bite as rounds, but very comfy on the fingertips. TBH I never even knew there was more than one kind of string and couldn't figure out where some of those vintage sounds were coming from. Still won't be my #1, but fun to try at home. They cost twice as much, but I figure I won't be changing them anytime soon. Is it true there are players who never, ever change their rounds?
... or when you've just read a lot of praises on another type of flat wound strings here on TB, which successfully made you GASsing for them, but you have no other eligible bass to put them on.