I had flats on my P Bass for most of 26 years, but got a wild hair and changed them out for RS66 Swing Bass. I'm surprised how versatile and even organic the strings can sound with the EQ set flat; using my hands for tone variance. I know it seems a round is a round, but the Rotosound metal has a unique sound and how it reacts with Fender Basses is really special. As the Rotos have aged they've become just right for any style. I'm a long time pro and have a de-facto recording bass which is a stock vintage Jazz with Swing Bass steels 45-105. A Jazz with Swing Bass is great for everything thrown at me.