I think for 500m it's splitting hairs, and as Brawlo mentioned it is only worth considering if you are very proficient at transitioning... and, it should go without saying, very comfortable putting such high power (not 2 minute power) in aero position. I had very little bike time this year, and zero time in aero bars, so the choice was easy. Still, my chief nagger commented on the video:
I do watch it and think: "That's a guy who should be in aero-bars for that event"