Dear Angus,
I own a Congo 90mm, an Angulon 90mm and a wide field Ektar 100mm. These lenses are coated, not multicoated. And the WF Ektar is far more better than the Congo, easier to find used and less expensive. And the image circle of the WF Ektar is greater than the Congo. The Angulon is today outrageously expensive and the image circle is OK for 6x9 but not for 4'x5'.