I enjoyed EvLification's version of "Essential ED-E and Rex" but once ED-E has been upgraded the Essential flags go away, this is a simple FNVEdit that restores the flag on the upgraded ED-E.

I didn't upload any pictures because other than killing ED-E to prove he can go unconscious there isn't really much to show.

Just drop it in your load order below other mods that alter companions and you should be good to go!

All credit goes to EvLification for the original mod, I simply added what he did not.
Also don't forget to endorse his file! http://www.nexusmods.com/newvegas/mods/50540/?