I never bonded with bass half-rounds (which is technically a D'Addario product name). They are kind of sticky/coarse feeling, just in a different way than rounds. Tone wise they sound far more like rounds and I would actually struggle to assign much of any flatwound tone factor to them, other than reduced string noise. I did however find the Half-round 6 string electric guitar strings to have some likable qualities. I like them more than roundwound guitar strings but I don't love them as much as I love flatwounds, so they didn't quite win me over in that arena either.
If you're looking for a best-of-both worlds option, I would recommend GHS Pressurewounds (which aren't ground down rounds, but rather rounds with the outer winding pressurized to an oval sort of shape if you looked at a cross-section) which have a nice nickel-round-esque top end, but legitimately pack that big low-mid punch that I love in flatwounds OR Ernie Ball Cobalt flatwounds, which are true flatwounds but almost the same amount of bright top end sparkle as rounds.