Me too -- dang has given me valuable feedback about what kinds of things to post, and how to focus and frame posts so people will find them useful and interesting, how to save and respect people's time, and how not to overwhelm or tire people out so much. Much of that advice applies to writing and life in general, not just posting to HN! And he's even done kind favors like correcting an embarrassing typo I made in quote of a transcript that accidentally inverted the meaning of what the person was trying to say, when I only noticed it after the paint dried.
He’s helped me a couple of times to make my posts more appealing to readers, providing great insight into what HN readers are looking for.