The only problems I see with the “Open Documents”:
1) The ContextMenu of “Open Documents” is missing items that are on a ‘real’ Tab’s contextMenu.
2) †Disables, right-click + Scroll from cycling tabs (when it is focused.
3) It would take up the left(or right) side plugin location.

Although I did forget about that particular plugin, It’s similiar to Opera’s Window Panel, as opposed to tabs on the left/right — it feels less “solid”.