Which in your opinion is better for SEO? To have a long, keyword optimized first page with links to new posts in the sidebar, or a blog type first page where the first page changes with every new post published?
And how many words does your first page usually have? I put around 600 to the static first page and the blog posts are 300-400 words long. Would it be better to have a 1000+ words homepage?
It depends. If you can write relevant content for your site. You can also try both of the method discussed above.
The main problem here is the fact that you should always include the right amount of keywords into every single post, not to mess up your density. And I'm sure that regular content update refers to your site in general, not just your homepage. At least this is logical to me, I hope Google sees it the same way.