I am not sure. But as you noticed already link exchange is not so effective nowadays. I read a few days ago that Google is going to integrate new algorithm where reference weight will not included and will not give pluses for SEO. One of the main property which Google is going to estimate, it's user's queries and your content. The more your content is matched with users queries, the more weight your site has. I'm not sure that this is true, but I read it on the Internet
