Agreed on it making a difference in competitive play. Though 200-300ms is a pretty slow response time (especially in a competitive environment - depends on the game I suppose). In most twitchy games (actually in most games) people's reactions would be in the 20-100ms range.
One of the interesting things that can happen if you v-sync a game that's capped to 60FPS on a screen which has a refresh rate that is not a multiple of 60 (e.g. 70 or 100, etc) is the addition of mouse lag to the game (there's an added delay between moving the mouse and actually seeing the action happen on the screen).
One of the interesting things that can happen if you v-sync a game that's capped to 60FPS on a screen which has a refresh rate that is not a multiple of 60 (e.g. 70 or 100, etc) is the addition of mouse lag to the game (there's an added delay between moving the mouse and actually seeing the action happen on the screen).