I'd love to be able to place 1 photo above/across 2 artboards so I don't have to create the same layer on each artboard and line them up. Is there already a way to do this or would anyone else appreciate this functionality?
I believe that it is one or the other (a single large canvas where you use guides or slices to break up the overlapping content or "separate" artboards). Photoshop only supports a single canvas, it is not a "multi-page" program. Artboards were a creative hack to layer groups to achieve multiple canvas/pages in a single document system.