Not all units have the luxury of mode S; it certainly makes ATS provision a lot easier and you get a real feel for how your area operates as you get familiar with call-signs and routes (7k aircraft). The downside is, mode S equipped aircraft are indicated with a small dash next to the label box, and the amount of 7K squawks I see with no altitude (i.e. equipped but not selected on) is staggering. But then again . . . . . .
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