PG, you just got me wondering about feedback. When you let people you trust or respect read drafts of your essays, what kind of feedback do you expect? How does the feedback affect your essays?
I don't have any specific expectations. Usually I just say "please let me know if got anything wrong, or missed anything important." If I'm writing about something I don't understand well enough, I ask domain experts. I always ask Hutch Fishman about startup funding, for example.
I take responses pretty seriously. I've killed whole essays friends thought were bad. Usually I just have to rewrite a sentence or two.