I have a couple of reservations on UA 881/882 in Nov/Dec. My awesome 15A seat assignment (on the 747) was "preserved", meaning it would be 15A on the 777. Switched them all to a more "desireable" location.

Thanks for the heads-up.

Edit: It is interesting to view the seatmap for UA 881 on Nov 1. No E+ seats are assigned at all, I assume this is because many of those reservations holding E+ seats on the 747 had their seat assignments remain the same row number when the aircraft change was made, even though these are all E- seats on the 777.

Futher EDIT: As of today (9/9), UA put 747 metal back on this route.