Response time helps reduce ghosting. 16ms has some noticeable ghosting at certain times, but it's not a big deal. 12ms is barely noticeable, but I highly doubt many people will notice a difference between 8ms, 5ms, and 2ms. Think about it - 8ms is equal to 125fps. 1000ms in a second / 8 = 125. However, the refresh rate on most LCDs is still at 60Hz, 72Hz, or 75Hz. Once you're in the sub-10ms response rate range, there are other far more important factors in choosing an LCD - mainly color depth(!), contrast ratio, brightness, and viewing angle.