I don't have a 'show HN' thread. But if your target market isn't HN, why the hack would a 'show HN' thread contribute anything to growth?
HN has the ability to make something go viral in various segments. I did some work for a company that posted a Show HN thread and it was picked up by a general online newspaper. It was engineered to get bloggers and twitter users to write about it. Twitter and G+ picked it up, and the paper found it on the same day. Then other segments found out and started to blog/tweet about it and the effect lasted for more than a month. It all started here. All of that, plus investors got in touch with them. Which IMO, is one of the factors that makes HN very valuable. The investment community pays a lot of attention to it due to the fact that this is a YC product.
It seems to be one of the biggest misconceptions out there right now. People think you can just make a few posts on HN & Reddit to fuel the growth of an entire business. It worked for a few, such as Imgur, but it's not the norm.
It is said that the great majority of startups fail. Maybe this is the reason: many of them lack basic business common sense?