Never had a yellow staining problem (and I'm surprised to hear that has diminished for you, but that is good news all the same), but at 1500+ hours the dark vertical bands are just as visible (and distracting) over here as the day I got the set.Just an update for those curious. I'm 5 weeks and 385 hours into my 512 build 65EF9500. Still 1 week left in my Best Buy 6 week return window.
The picture quality has improved over time for me. Yellow staining on left edge which was there on day 1 is SIGNIFICALY reduced now. I cannot perceive any yellow stain or dark banding during any content watching or game play.
Using calibration slides I can still detect a few "defects", but I've come to accept that what I can perceive during normal use is all I really care about.