Heh, I did try it out first - it came out as the string ON. 'Course, if you just do defaults write some.domain somekey true, that'll also make it the string true instead of a boolean true. So I knew it would convert the string true to boolean true. I hadn't actually looked to see if it converted the string on to boolean on/true/yes/whatever-else-it-may-be
But ShowAllFiles instead of AppleShowAllFiles never worked for me on 10.0.x. I thought that tip was just false until I found one that said to do AppleShowAllFiles - that one worked.