Sounds like a winner. I can't see why he needs pledges instead of investors. I might be more willing to put a few thousand into a Venture Capital fund for the purpose of getting it off the ground than I would be to pledge.
In any case, I would prefer a flat glass, 36" by 18" control surface, with everything I could possibly want placed where I could easily edit with two hands, and when I need to type, if voice recognition needs a little assistance, then a keyboard could be made to pop up in the middle of the glass where the jog wheel was.
In the meantime, I could see this as a reason to buy an iPad. Pledge $100, buy an iPad, buy a few apps, and build the prototype. Sounds quite reasonable. If I had not just blown the budget on a camera ....