Fwiw I made a point of looking at that middle J seat when I flew last week. Seemed a tad narrower and more coffin like than the A380 UD equivalent. Glad I swerved it now. In the end I actually swerved J altogether due to the relatively modest Avios outlay required for me to convert 7A to 1K on my return leg.

So I somehow STILL haven't actually tried the now not-so-new J offering fully (having a low longhaul type of year due arrival of 2nd nipper).

But F on the 789 was a great ride fwiw.