You have the answer for everyone right there in Reference Tips. You allow THE USER to decide how they want to interact. They can choose to Hover or Click.
Page Preview you give the user no choice - it's either off or on.
Why?
I hate them. It's the most intrusive reading experience I've ever had on any web page. And how do you turn it off? By interacting with the very thing you want to go away. Just terrible.
Again. Why? Why can't I have the ability to click on it if I do want to use it?