I used Rotosound Swing Bass for years; I used to love the tone (does anyone else remember the line on the back of the pack-"Thank you for your esteemed patronage"?) but when I got my Squier VMJ fretless I decided to 'go flat' and put some D'addario flatwound chromes on it.
I love the tone, it's pure bass, almost an upright type sound with a nice nice bit of growl there too. They did feel strange at first, (a bit like driving on black ice ) but I got used to that pretty quickly. They do have a higher tension than the Swing bass, there's a lot less give under my right hand. If I'm totally honest that's the only thing I dislike about them, but it's a small price to pay for the tone.
All the best,
Rob