My wife and I just flew KOA>DEN and ended up on the version without seats in front of 22A and F. I had paid a seat selection fee of $33 after booking on a layout with a seat map that showed the seats in 21A/F. The day before the flight we ended up being moved a couple rows further back. When I tried to change us back on the app it was trying to charge us another $33 to move back there. I called in and explained to the rep that I had paid for 22A/F already and she moved us back there.

About half the fleet have the new layout without the seat in 21A/F and the other half do, We were fortunate to end up within the layout that didn’t have the seat, so mega legroom for both of us. We also had the bonus of no one sitting in B or E. It did seem like normal legroom for B/C/D/E and the A/F seats had the tray table in the arm rest, so the seat was a little narrower and the armrests couldn’t be raised. I would definitely try to get these seats again. The buy up for row 21 was around $180/pp, which I considered doing but I could tell the plane we would end up on was the better layout. Out of a major hub there might be more of a risk of a swap. YMMV