Many years using Rotbass 40s (nickel Swing Bass with no silk) and I've never had a bad set. As all my basses were strung with them, and all in use, I got through quite a lot of 'em! All good.
The only thing I did not like about Rotosound was when they stopped making Superwound 505s. Best bass string ever. Contact core pressurewounds. Great on any type of bass, fretted or fretless, easy on fingers and frets. If they re-introduced them, I'd even dump my TI Jazz flats to change back.
Their local rep, Roger Channing, is always good and knowledgeable. Also a fount of knowledge and experience of playing in tribute bands (Upbeat Beatles, and damned good they are too). And when he was on leave once, Jason visited instead! Great team of people.