SARowl,
And what is that symmetry worth in pounds/dollars? Theory of uniformity is nice, but someone has to pay the bills. When a person who has no fiscal skin in the game lists hard, frozen requirements, he is usually standing for the biggest, most expensive solution.
Let me ask it the way it is really played:
Would you rather have 6 superwonderful fun machines, or 9 in a mixed fleet? For a fixed initial/operating dollar, which gives the most area covered, and least response time, and the most lives saved?
When someone starts listing requirements, and doesn't understand that the equation is fewer big ones or more smaller ones, that person is usually not invited to the table for round 2 of the decision making cycle. Don't get me wrong, my alma mater makes the BIG one, so I would perhaps think otherwise.