I have a set of TI Jazz Flats on a 34 Modulus and have to say that I've never been that fond of them. They are both low in tension and light in gauge, so they don't sound or feel very meaty to my ears.
On the plus side, they are brighter and have better intonation than most flats. The materials feel expensive and more precise. They have a relatively rough surface - I remember reading somewhere that they make them by winding a very thin wire in parallel with the final metal wrap, then remove the wire afterwards. The tiny gap left between turns of the tape allows a little more room for purer vibration.
I haven't played the Chromes, but have played the LaBellas, which are a pretty traditional sounding flatwound - massive, big time thump. There's a LaBella nylon tapewound set that's really good with a sort of rough-polished exterior finish on the lower strings. They are an interesting combination of being brigher than most flatwounds but more thumpy too (notes die off more quickly). I have these on a Veillette 35 fretless 5 which is piezo pickup only, but I think they'd sound pretty good on a magnetic pickup bass too.
Also on the nylon-wound front, I've tried the Rotosound TruBass and they really don't work for me. These have a very hard nylon surface. The first set of nylon strings I had was millions of years ago, a set of black Fender nylons which have a relatively soft surface.
Speaking of Fender, I think the old Fenders may actually be my favorite flatwounds. They are massive, thumpy, high-tension and bassy but I love the sound of them, and they're probably as cheap as you can find flatwounds - probably worth trying. They still smell the same way when they're new as they did 30 years ago.
I've also had sets of half-round strings (wound as a roundwound, then ground to a flatter surface). Never liked any of these (I think I've had D'Addario and Dean Markley over the years).
I play roundwounds normally (Rotosound Swing bass on 4-string basses, GHS Boomers or DR Lo-Riders on 5-string).
For most of these strings, you'll need the normal truss rod tweaks if everything is in good condition. The TIs may require a little more work if you play with low action because of the big change in tension.
David Fung