While this does NOT answer my Delta 777 EC question, I was on a 763 Monday and I can report that the bulkhead EC rows (16 or 17 depending on which side of the plane you are on) have "tons" of legroom and no one reclining into to "your space" ... if you had enough carryon luggage, you could probably make and improvised lie-flat bed there was so much space. The next best EC seats on the 763 appeared to be the exit rows 20? and 21? which also appeared to be designated EC based on the headrest covers. The rest of the EC seats on the 763 were certainly roomier than "regular" coach seats (legroom) but paled in comparison to the bulkhead and exit rows.
Still hoping someone will report back on the Delta 777 EC seating ...
The 777 EC seating is nicer because you have an adjustable headrest and a PTV.