Reaction time may have not have anything to do with your ET, but I personally feel that it can give you the edge over your opponnent....The quicker you get off the line than he does the better chance you have on winning or if not, giving him/her a run for their money...
Trying not to Mash off the line is kinda Hard...especially if you got the jitters...It takes a lot of time and practice...
Here is a clip of a pretty decent launch...He is revin' at about 3K...(Fast forward to the 1:40 mark)...but don't know what his mods are or whether he's running slicks or Street Tires.