If you add some fields to exclude to the comparison, the Overview tab still shows:

Identical documents: 0
Different documents: 175237

But when I view the Differences tab - none of the fields are highlighted (the differences are only in the ignored fields)

I'd like to be able to see how many documents are considered the same, perhaps with an additional count.

Identical documents (excluding ignored fields): 1000

Perhaps the Differences tab should also have another checkbox, under the Show options?