Linklet caches the linked page, but doesn't cache referred files like stylesheets or images.
I think the cached text should be able to help the user to find another copy of the content online using Google.
I developed it without knowing Pinboard. Linklet is at least an alternate to Pinboard. It took a subtle difference approach towards the information management problem and may have a different goal.
What do you mean by "email increases metadata exposure". Your automatic signature in the email message? Linklet is not a social site. All bookmarks are private to yourself.