I just heard back from Marc regarding Blogspot. This is what he wrote:
The advantage is that only the blog-content is read and thus you can use all RapidWeaver theme settings and styling to display the blog posts.
Plus you keep your sidebar, menubar, and all of that, because it is part of your website.
You can use the CSS-part of the RapidWeaver page to add styling to each blog post part, like I have done on my blog (http://marc.vos.net/)
Furthermore, the stack offers display options just for your website, like placing the Categories a/o Archives list where you want them, the ‘interblog’ and the option to determine the order in which the individual blog post elements are shown.
Furthermore, if you know a bit of PHP, you add PHP code to, for example, the Interblog-part. I have done that in my blog to generate the ‘Tweet’ and ‘Google+’ buttons in the footer of each blog post - no need to add these manually to each blog post in Blogger. And here (http://www.transadminsys.com/news-and-updates/) I used Interblog to display 4 FontAwesome icons between blog posts.
And the best thing - use the most simplest of themes in Blogger and redirect your blog permanently (http://marc.vos.net/index.php?id=351987013902757179) to your own site, so visitors are always visiting your site, not Google’s
With the off-site stack, people are leaving your website and that’s not good in terms of conversion or SEO.