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.
There is an real-time system shared by all banks. I can see my remaining quota immediately updated whenever I made an exchange.
In your example, if you have RMB in your China bank account and withdraw RMB overseas, these are no currency exchanges at all. It's not relevant to the $50k exchange cap.