Sorry for the noise, but I just had another thought: Rather than adding a new option, how about we make the behavior dependent on the value of org-src-window-setup?
Basically, when org-src-window-setup is current-window, it never makes sense to restore the original layout. But when org-src-window-setup is reorganize-frame (the default), it always makes sense to restore the original layout. I'm not sure what the "correct" behavior would be for the other options however. Now that I think about it, I remember trying out the "current-window" option before, and having a very similar experience to Matt -- while I enjoyed having more manual control over the window layout, the fact that org-mode would change the window layout after I finished editing defeated the whole purpose of this, so I switched back to the original defaults.
