I found that the Cobalts have a similar thump on the bottom end as the flatwounds I was using - which is part of what I really love about them. I would say they have as much bottom end but it's maybe slightly tighter and seems even a bit deeper but they also have the top end zing of roundwounds. So, for me, they combine the best of what I like about flats and rounds. You may find the ping sound on the top to be a little excessive at first (not sure about your taste in this regard) but it does go away over time.
As for volume, they seem pretty even between the B, E, A & D strings. I find the G string to be a little weaker though. So, I lifted that side of my pickup to be closer to the strings to compensate. Of course, different notes will resonate more than others depending on your speaker cabinet or the room where you're playing.
EDIT/CORRECTION: After receiving my new compressor (FEA DE-CL, which is an awesome compressor/limiter btw) I started to realize that the G string of my cobalt string set is NOT actually weaker than the rest of the strings. With fairly consistent plucking effort on each string I see now that the G string is setting off the compressor and limiter as much as any of the other strings in the set - which tells me it's putting out just as much volume as the other strings.
So, based on that, what I'd say now is that the G string *seems* quieter because, I suppose, it's at a higher frequency than the other strings and therefore is not creating as big a resonance as the lower strings. This is to be expected for any set of strings but for some reason, maybe due to the increased midrange content, was tricking me into thinking that it was quieter than the rest.