> My feeling is HDM is to Dune what Eragon is to Lord of the Rings.
This is an interesting comparison. I have not read Eragon, but I have read reviews that say it's a transparent reskinning of Star Wars. Assuming that's true, the form of an analogy between Eragon and Lord of the Rings would be
Eragon : Lord of the Rings :: Star Wars : The Sword of Shannara
But that's one of those somewhat-malformed analogies where the relationships cross the :: instead of mirroring each other to either side of it. Like "Shakespeare : Tolstoy :: Romeo and Juliet : War and Peace"; there isn't actually a relationship between Shakespeare and Tolstoy, but if you have three of the elements, you can force the fourth.