I agree fully with almost everything you said. I guess we have very similar ears
I have been paying special attention to the bass of the KC06 and B3 and I also agree with your assessment of it. Essentially, bass conscious listeners will find problems with either of the two. The KC06 has ample bass imo but in layman terms, is slightly 'sloppy'. The B3 doesn't have the best bass texture either, but it is still slightly better, although it just simply doesn't have enough body for some people.
The only thing I don't quite agree is the part where you mentioned
poor separation and imaging. Sure these may not come close to the Havi B3, but they're pretty good as well, so
'poor' is a little too strong a word for this.
Unlike you also, I wouldn't say I prefer the B3 over the KC06. The airiness and clarity of the KC06 is IMO amazing enough to make up for where it loses points to the B3 in accuracy, reproduction/imaging and timbre.
I feel the best way to resolve this is as what you mentioned. One is more fun and engaging, the other more laid back and accurate. So... use both at different times according to either mood, or genre of songs you intend to listen to at a certain point of time!