After talking a lot with the designers of the new series, I think they can be describes as:-
Accurate - without being clinical or hard
Warm - without being coloured
I have found out that, although the microphone diameter is only 19mm, the diaphragm size is the same as the old 25mm diameter microphones!
The bass extension on the directional capsules goes down to a genuine 30Hz (lower than most other directionals), the omni goes down to 10Hz.