It's important to realize that "marketing site" and "frontend" are totally different things. If it's truly just a informational site, WP is probably fine. But

It's important to realize that "marketing site" and "frontend" are totally different things. If it's truly just a informational site, WP is probably fine. But, I would not build your app's UI, or even purchase workflow, in Wordpress and then your real "app" in Rails.