Fluctuating brightess is a thing of the past. It affected early production models about a year ago today. Even the ST30 had it. I thought I was seeing things...I may have even noted it in the ST-review a year ago. But things have changed since. Firmware upgrades on both televisions corrected colour accuracy issues. New production models around July or after eliminated fluctuating brightness. Samsung also had the FB issue. As of their November builds, on the 64D5x0 model, the FB was still there. I know because I bought one. It was very subtle, but because I noticed it being the video guy I am, once I saw it there was no going back. Amazing picture for the price, though!! Samsung...pull up your socks!!