When first powered on, the EG9600 was plagued by uniformity issues, but you really can't see them during content.
Even after 120 hours of continuous use (running a standard color bar pattern), the initial uniformity improved, but still hadn't evened out entirely. After doing some research at some of the more TV-geek friendly corners of the internet, we found that OLEDs benefit from regular down time during the initial break-in period.
After leaving the TV off for a night, I went back in the morning and voila—it was like looking at a different screen. The edges of the panel were still a bit dark compared to the center, but the vertical banding was completely gone.
The EG9600 at 20 IRE after about 200 hours of use (calibrated). Edges of the screen are still a bit dim, but much improved overall.
And quite frankly, as jarring as these uniformity issues can be during test patterns, it's hard to even see them outside of special circumstances. As they tend to present in darker grays, you'd need to be watching something where a sizable portion of the screen was taken up by a uniform gray color. Before deciding if OLED is for you, make sure you give the TV a good 100-200 hours of non-continuous use—and ask retail staff how long their showroom OLEDs have been running, too.