Woah, never heard of those. Good to know
back in the 80's they were quite a thing. think about Mark King, in Level 42

Rotosound came out with this "funkmaster" set of strings consisting in 30-50-70-90 strings.
even Geddy Lee used them for a while, and I think even Nick Beggs from Kajagoogoo used them. many other players use 35-95 strings, like Stuart Zender from Jamiroquai.
they are wonderful as soon as you get used to them: the left hand get used immediately, so free on the strings, but the right (plucking) hand takes a while, because they are so soft that bend "against" the fingers.
one of my favourite thing about light strings is that it's easier to alternate a "clean" sound to a "dirt" and clanky sound only with the dynamic of the fingering and they feel like they have a compressor always engaged, becasue if you play harder, ad a certain spot of "hardness" they won't play louder
so you can alternate fingering and slapping without anything in between, or, as mentioned, switch from a soft and clean sound to the dirty and clanky without the extreme raise in volume.