First of all, welcome to the forums! I think you are exactly one of the kinds of people that the Bitcoin community needs. I think I agree with all of your points, and it's refreshing to see them expressed with such clarity.

I'm very interested in this as well. I've been thinking about doing the same, and have heard it suggested several places. I'd really like to hear more about your thoughts on doing this.

My first thought when considering this, is that I fear it's sort of a rigged game. I mean, US Treasury bonds are denominated in a currency that is controlled completely by the Federal Reserve. As far as I can see, the Fed could (theoretically) drive up the price of Treasury bonds to any price it desires. I mean, it creates the very currency that these bonds are denominated in. As far as I can see though, it would require the Fed to purchase bonds directly from the US Treasury, instead of in the secondary market. Or am I wrong on this one? How is the price, that your short references, determined? Is this by the price in the secondary market?
This is probably the thing I fear the most. The political system isn't exactly thrilled about speculation, and I'd imagine shorting US bonds is one of the least favored speculation activities a US politician can image. I don't think it would be far fetched to imagine political action that aims to drive up the price of treasuries temporarily, to get rid of the leveraged shorts. Or am I out of line here? I'm just bothered by the opacity of this market, and I feel like I'm trading against politicians instead of the market.

With regards to the actual process of shorting the bonds, I have a fair understanding of how it works. I presume you pay an interest on borrowing the bonds from someone. At which interest rate can you borrow the bonds?
I figure this must weigh in on your decision, since a high interest rate will make your position unprofitable quicker than a lower interest rate. Do you have any time estimate on when you expect the bonds to start declining in price?