As someone who has used Opera since version 4, historious is much superior. I have never been much into bookmarking, I have about 50 bookmarks now and the list is already unwieldy, even though it's categorised and synched. I just never look at them.
In Opera, you can see the titles, and you're lucky if you can make out the title of the item you're looking for. On historious, you just search for "nginx ubuntu" and it finds the document, even though the title may be "So and so's blog | Webservers".
Another thing is that, with historious, I don't have to think about where to put the bookmark. I just click the button and it's done, I can look at it later or not, it's always going to be there, even if I forget about it. I find myself searching historious first and Google later, as I usually find things that relate to what I want to do now which I had found interesting before but then forgot about.
Do give it a try, it's really changed the way I bookmark, and I love Opera to bits.
EDIT: Not to mention that I can create a custom search where typing "hist <keywords>" will immediately take me to the first result in my historified sites!
About the demo, we should make it more obvious, but there's a hint that says "try searching for historious". We can't include too many things in there, as everyone searches for different things and we'd never get it all :/
I haven't wrapped my mind around your concept completely yet, and I didn't get any hits by searching on your demo, so ... :)