I use a 4:3 tv but watch HD stuff and widescreen movies (and video games which don't fill up the entire screen despite accurate geometry. Gee, thanks Rockstar). I've got some gray bars due to the uneven aging of the phosphers. Will it help any if I run some 4:3 content to fill up the screen to help the "younger" areas catch up to the more used areas?

Thanks.

You would have to reverse the light areas. Running fullscreen stuff would just age them both at the same rate, leaving the gray bars visible.