I think firms would say they welcome diversity in all forms, including interpersonal - that the reflective personality who needs time to digest and analyse before speaking is as welcome as the forceful, extrovert. My experience is that it's sometimes almost impossible to distinguish between many people as they are all very, very similar. And it's the extroverts, the talkers, the expressives who seem to be everywhere. After all, part of this is being visible to clients - it's about showing them you are there and demonstrating value. Of course you want to do this with good work but people are people - the visible, the loud, the energetic are seen consciously or not as 'contributing' more.