Just curious: I have to do a mini-CMS that allows users to add "pages" using a template. Each of the produced pages has/is an entry form and a "received" page.
I can visualize this in Rails pretty easily, but I'm wondering if there's any advantage to using a CMS like Refinery. Thoughts?
I was supprised to see Phil Arndt's answer voted down - I guess that it's hard to gain trust if you're involved in the product you discuss.
As for your question: sure you can build that site yourself, and most likely it will be simpler and will cost you less time than diving into the RefineryCMS documentation.
However most likely this site will evolve, your client will come up with more requirements, and it'll become harder to keep up with the complexity of the project.
Further more, you'll get more similar questions from other clients. Similar, but not identical, an you'll have to start from scratch every time.
A cms framework such as Refinery becomes an interesting choice at that moment. A framework gives you bigger building blocks than the Rails framework itself, so you can build faster. You won't have to reinvent the wheel for every customer request, since it will often be similar to what other people have built and shared (the "engines" in the case of Refinery). So the time you invest to learn to use the framework will pay off.
So in your case, even if you've already implemented your mini-cms, I'd consider redoing it in refinery or another framework CMS before you end up building your own CMS in which you'll have to duplicate all of the work already done for other CMSes...