I used to have comments and a xapian index/engine on my website, something I wish every website would have. To share my experience, I eventually removed both.<p>The xapian index was both faster, more accurate and up to date than any public search engine. Nobody besides myself ever used it, often returning from a google site: search instead.<p>Things change if you have the wiki as a personal information repository and use search yourself, as the OP points out. I still have that, but I keep this private as I also index other private stuff and can't make the two separate.<p>And because I have a local mirror of the archive anyway, I'm often faster grepping than using search (it's just not big enough).<p>I also had fully open/anonymous comments. As you might expect, this gets spam almost instantly nowadays. I switched those behind a login wall, but I realized after a few years that I wouldn't create an account on a random website myself just to post a comment. For anything more involved than a quick comment I just dropped an email to the author[1].<p>Right now I fear that under GDPR those public comments would just be a liability.<p>[1] if the author is kind enough to do so instead of dropping a twitter handle...