This is awesome, and I feel that this is indeed Alfred's Clipboard Manager on steroids. You did mention trying out Alfred. Without installing ClipBook but reading up on the features, what is missing from Alfred?

Alfred's Clipboard Manager is pretty navigable with the Keyboard; the history is as much as there (I don't know about being infinite), and I can also see the preview, etc.

I used to have Clipboard managers, but with Alfred + Powerpack, I did away with another program running on the menubar/background.

Edit/Update: I just checked Alfred and I can keep plain text, images, files list, for 3 months.