Also investing the time in creating some more impressive animations would really sell this to people. If you don't have the knack for it yourself, outsource it to a designer or, dare I say it, make a competition out of it.
Anyway, I hear what you say about the need for impressive examples. I don't have the talent for that; my current examples are certainly not too interesting.
I guess I'll have to invest some money into it... (Since Radi is free, it's not making me anything, and so far it's been strictly a hobby project. Maybe it's time to take it a bit further.)
Here's a screenshot: http://radiapp.com/radi-windows-sshot-20110805.jpg
I haven't looked deeply at Edge since the initial release. One fundamental difference is that Radi's output is completely custom rendering into either <canvas> or <video>, while Edge uses CSS for animation. I wrote a blog post about that with lots more detail: [1]
Although there's some overlap, the approaches are basically complementary. Hence I'm hoping to make Radi into not so much a competitor to apps like Edge and Hype, but rather a more creation-oriented tool that can be used together with these other apps that focus more on building entire sites.
Now that e-books are becoming basically HTML5 packages, I'm hoping to find some opportunity for Radi in that market as well... But I haven't done any deeper research into that yet.
[1] http://lacquer.fi/pauli/blog/2011/08/why-radi-uses-canvas/