Other than "jobs" we get no help promoting content.
I actually think being a YC company can hurt you because all your YC buddies vote for you and then it appears that your cohort is a voting ring. I actually have to tell people NOT to vote for my posts sometimes, lest I trigger the HN Gods' wrath.
I guess I wouldn't call it a disadvantage because saying "boo hoo, my friend and I from YC up vote ourselves too much and we get hit by the voting ring detector" is obliviousness by omission. I assume my links do well on HN because I went through YC and have written about going through YC.
My real point is to highlight: (1) There is no advantage on HN to going through YC. The only changes are (a) You have access to the part of the site that lets you book office hours (b) You can see other YC users and (c) You can post jobs. I know of no other benefit. My co-founders can't, for example, down vote comments because they don't have the karma. (2) A significant percentage of active users are YC alums, YC alums that know me, or people who know me personally, so once something I post hits the front page I ask my co-workers and my friends to NOT up vote me. I do that because historically my items have gotten thrown off the home page and I write blog posts so people will read the posts.
I actually think being a YC company can hurt you because all your YC buddies vote for you and then it appears that your cohort is a voting ring. I actually have to tell people NOT to vote for my posts sometimes, lest I trigger the HN Gods' wrath.