Yes it is hard to detect at 85hz. I only notice it on the edges of the screen (the picture even seems to move in and out slightly)... anything lower than 85 an it is fairly obvious.
Also, below 80hz is nice too depending on the souce. Have you played a game at 75hz or even 60hz? The flicker is almost invisible even at 60hz while gaming, though not completley.
Edited by De-Zant - 8/12/11 at 10:24am