Lost me when he said the fig 2 appeared to have a more even gradation than fig 1, and not just because of the spelling error. The fig 1 looked more even to me, but I am colorblind.
It's always refreshing to meet people who never make spelling errors! :) Other than that, try calibrating your monitor!
Ok, I went further and became even more annoyed. I think in all of the examples the linear images looked way better. Could be due to the gamma correction my Mac does, or maybe the authors opinions are vastly different than mine.
It's not an opinion, check the references section for further info.