For the low fidelity comps, I bought myself a LiveScripe echopen so I could draw out things and import them for manipulation, instead of throwing out paper, etc, but I haven't explored it to its full potential yet. The benefits are that I can easily import and manipulate drawings and that I can record audio as I draw, and then click on a drawing to hear what I (or clients) said at the moment I drew what I clicked on. Very helpful for remembering all the ideas and flow when I get to a computer.
Your solution looks fantastic for low fidelity. It would be super cool if I could control it with that pen like this: http://www.livescribe.com/store/20070723002/paper-tablet/p-4...
The next step is when I start replacing low fidelity with medium fidelity photoshop mockups. Once approved/done, it goes to real graphic artists and coders. It would be great if I can easily copy selections of a photoshop comp over specific parts of drawings to move it's fidelity up the ladder piece by piece and page by page as components and pages are done, and get feedback on it as I go. With an easy way to keep track of what has been updated recently or commented on and by who, and a way to mark off comments that are addressed, and to know who has seen what and if they approve or not with comments.
The other thing I wonder about is how you organize things. I'm currently designing a giant app for all platforms. The specs are huge and it has lots of subtle animation state changes etc that might be challenging to map out, where clicking makes just one bit of the page do something, not going to a whole page. (Like opening a menu or flipping a card to see what's on the back.) It would be nice if it could somehow deal with that and deal with reusing sections on several mockups for different media. I'd want to switch between the same page (if it exists) for tablet, phone, and PC. And when I upgrade the fidelity of an elment on one mockup, it would replace it everywhere else it is used.
So, that's my initial thoughts on what my dream wireframing tool would be.
Generally love what you are doing and want in immediately to see if it speeds up things for me! :-)