I spent an afternoon uploading geograph images last
week. Loads we
didn't have and were better than our coverage.
What do you mean by "our coverage"? As I said, the project goals are
not identical. There is no requirement to have images from every
geograph square on commons. Lots are encyclopaedically irrelevant.
I'm sure it was discussed here before and decided against.
Unfortunately the ml archives are not searchable.