Train wreck getting render_to_string to work from foreign controller [SOLVED]

Just for collective knowledge as I have found no info on this problem online:

I solved this by adding an .html.erb file for the “missing template”, since by design or bug Rails3 will not find or render another controllers view (in my experience). Then in the new html.erb file, I just put <%= render “comparisons/display” %> because the views are able to find templates from another controller.

It seems like this is more work, but I can see that perhaps this was done by design as it forces me to more cleanly define what the controller actions render.