Completed my first sCO BF longhaul today on a 772 IAH-NRT. My thoughts:

• The seat layout on the sCO 772 beats the sUA ones hands-down (2-2-2, vs. 2-4-2 )
• The sUA seat itself is much more comfortable in most respects. The footwell seems much smaller on sCO, to the point I had problems with it (one of my feet kept going to sleep due to the cramped space). The overall seat length was not noticeably different to me. The legrest is too narrow and can't be raised as much without reclining the seat more toward bed-mode than on sUA.
• The sCO BF crew was a hair better than most sUA C crews I've had on flights to/from NRT (with the exception of a fantastic crew on SEA-NRT a while back). The purser came by and thanked 1Ks and GSs by name, and FAs were quite attentive during service (and weren't grumpy, which is a problem I've had with sUA crews before).
• IFE was inferior; interface wasn't as good, and for those who enjoy the map (and of course Ch9), the map itself wasn't presented as well. Selection of films and shows was so-so.

For me, the seat layout is the winner. I can live with the less comfortable seat to be able to be in the middle 2 and not have to climb over seatmates to get up during the flight. I can live with lesser IFE so long as I have in-seat power to run my own.

I still prefer the UA 763 C seats for having the better sUA seat + 2-2-2 config, but when choosing between sUA and sCO 772 seats, the sCO ones win.