The chromes are great, but will give you a very zingy sound, especially at first, for flats. The Detroit Bass flats from webstrings are awesome too. Deeper fatter flatwound sound, without the tension.
I have some DR flatwounds on one bass and the Detroit flats on another. Both have that great thump of a flatwound, but the Detroits from Webstrings are much nicer to play. I have never done any measuring of the tension or any type of comparison from any posted specs, but the Detroits just feel so nice!
And they are 19 bucks a set!
www.webstrings.com