I was scheduled on a ORD-CDG flight earlier this month. They showed the old 763 until about 24-48 hours prior to the flight. Then they switched to the new 763 for about 12-24 hours before they reverted back to the old 763 ~ 6 hours before the flight. The J section left fairly full except for 2-3 empty seats.
I will have to wait to try out the new 763 some other time.