The scenario is that I have a lot of FieldRenderers. These should output data from various places, some from item X and others from item Y. And should be outputting properties f
I understand you want to be able to do this on the front-end like in MVC-style and not in the code-behind, but that scenario seems to pose that a front-end FieldRenderer control may not be the right tool. I obviously saw the code you wrote in your answer but why not do this then, all on the front-end:
<%= FieldRenderer.Render(item, "field name") %>
E.g.
<%= FieldRenderer.Render(ItemX, "Logo") %>