In my experience, diversity in temperament is essential for any team to function. If you put two people who are highly excitable together, they will keep runnin

In my experience, diversity in temperament is essential for any team to function. If you put two people who are highly excitable together, they will keep running after new ideas and feeding of each others excitement. If you put two optimists together, they will tend to gamble and play too risky. If you put a team of idea men together, you tend to have designs and nobody doing the actual work. I believe every team should be made up of a bunch of slow and steady chaps, and a few creative people, with the creative people split into excitable and careful. The guys that one often assumes are slow usually have really good solutions, but when the team is too fast paced, those ideas get drowned out by the people who are loud and confident of their own ability. Soon, the quiet chaps stop talking, because they know nobody will listen to them. Diversity has nothing to do with ethnicity if you are faced with a programming task. If you were to solve a socio-cultural problem, then diversity in terms of ethnicity would probably be a good division criteria.