It's hard to get a percentage of players of older editions versus the current edition if there's no choice of "I don't play older editions."
Which I don't. I tried a retro-game for my bachelor party. We did hardcore 1st edition Tomb of Horrors. While I still like the module, I didn't care for the mechanics anymore. To me, they seemed unneccessarily arbitrary and restrictive. Although, I do admit it was fun killing one of my player's characters three times in a row.
JediSoth
edit: changed "one of my players" to "one of my player's characters" so it didn't look like I was committing murder