There is definitely a trade-off. I like the thumpiness with flatwounds, but its true that you lose some of the "hi fidelity" you get with roundwounds. Flats have worked well on many of my basses, however I just bought an expensive custom bass, that just sounded
dead
with flats, but it opened up beautifully with rounds

. So I think it comes down to the type of music you are playing, and the instrument itself.
Stay away from the half rounds, they feel terrible to the fingers, somehow oddly abrasive ( IMO).