Hmm.
Will you have a folder for your blog? Something like http://www.domain.ext/blog/<topic-or-category>/articles/<article-name>? I think I found your site (wednet) and it looks like you already have a blog and a few other important pages in the root directory. </article-name></topic-or-category>
I would NOT park the articles themselves in the root domain. While you want a flat(ish) architecture, you don't want it to be completely level; you want your most important "money" pages in the root directory. If you have 15-20 categories and 3-15 articles per category, you'd have between 45 and 300 posts in the root directory and that's too flat.
If it were me, I'd go with http://www.domain.ext/blog/<article-name>. (Notice I removed "/<topic-or-category>/articles" from the example you provided.) You can use Wordpress to set up topic-or-category pages e.g. http://www.domain.ext/blog/<topic-or-category>/<article-name>, but these should be noindexed. They're there only to make it quick and easy for your audience to find what they're looking for. </article-name></topic-or-category></topic-or-category></article-name>
At some point you may want to start indexing your category pages. There has been lots of discussion about that on this Q&A. It's a personal choice and it can result in increased traffic and conversions BUT you should make an effort to customize category pages so they are absolutely unique before you decide to do that.