After reading more about using Discourse for comments I've realised that it's not a good fit for me. There is a solution for Discourse where you can get X number of the best replies shown under a blog post or article. But you will not have a "leave a comment" area under the blog post, the reader will have to go to the Discourse forum, sign in and then leave a comment.
I can see that this might be a good idea for larger sites with lots of comments and where you're trying to build a community. It looks good over at Codinghorror's blog, but I think it's the wrong solution for me, for now. And you can't leave a guest comment when using Discourse.
Jeff Atwood's (@codinghorror) answer to the question:
Do you have any plans to enable in-post and anonymous commenting via this plugin? - @erlend_sh
makes it very clear that they do not intend to support guest comments in the future either:
No, none whatsoever. - @codinghorror
So Discourse will not be my choice now.