I know Kass is a bit of an semi-introverted character but pairs up well with Motya's stupidly extroverted personality. Zeph's character (if I remember right) is kinda mid-line between the two and generally angry. I remember Night's character being very disciplined but not really introverted. Mal, when Orion returns, was a very extroverted character, Hansa's Nasir seemed to be the wall flower type, and Hank's character seemed to be a very dark introvert.

I would say go with whatever you are comfortable writing. The dynamic of the group doesn't have to be perfectly balanced and it is often that imbalance that creates good interaction. I think at the two extreme poles you have Motya as the extrovert paragon and Hank (I may be wrong) as the Introvert Paragon. 

Fall somewhere in there as long as you can write it out easily enough and it "seems" right for the character you have in mind.

My two cents anyway