I bought an ASUS 21.5" 2ms Full HD 1080P LCD a couple days ago(hasn't arrive) and I've been asking myself if the 2ms response time will really make a difference. Is it true that the human eye won't notice anything faster than ~8ms? If you have seen 2ms and 5ms monitors, is that a big difference?
essentially those are the refresh rates that would limit the response time in order for you to notice any artifacts. Consequently, if either monitor is hooked up to a rig that is putting out 60hz video, you won't see any difference.
as far as can human eye notice anything faster or slower, yes a human eye can notice things faster than 8 ms, it depends on the conditions in which an eye has to notice things. But as far as your ability to tell between 5ms and 2ms - human brain has no way of distinguishing even if the eye can.