I went ahead and took video to compare with a metronome. The time you have to push the right button is significantly under 1/2 second on my game. Average human "choice" reaction time is at least 1/3 second under more favorable conditions than a console game can usually give you (due to four different buttons and various types of lag), so it's pretty safe to say that this is near (or past) the limit of what most people can pull off most of the time, even with practice. On a personal note, I've tried about a dozen times, 4 of which I got one button on, none of which I got two on. I'm trying to figure out if I can reduce the lag in my TV enough to help.
(New game, hard core, 4 points in decryption on Shepard, the first one on Eden Prime, download, not disk)
