I've just done so, and I intend on keeping Web History turned off. I simply do not derive enough benefit from having this data around for myself (when's the last time you benefited from Web History), and unlike other permanent data such as G+ posts, comments etc I do not self-censor searches that I would like to conduct, so I find it very plausible that someone with more processing power than me could find out more about me than I intend.