I love outliners but I am firmly in the single pane outlines camp like Ecco Pro and Omni Outliner (org mode also?). For some reason, I just can't swallow the tw

I love outliners but I am firmly in the single pane outlines camp like Ecco Pro and Omni Outliner (org mode also?). For some reason, I just can't swallow the two pane UI. I wonder if there has been any usability research on which model (single or two pane) is least obtrusive to flow of information to and from the user.