The only way to attack Bitcoin is to follow it's rules. The problem is not that Bitcoin rules can be broken. They can't be because you'd need to convince everyone to change to a different Bitcoin client with different rules for that.
Our whole point of disagreement seems to be centered around this one statement. You seem to believe that it is absolutely 100% impossible "to convince everyone to change to a different Bitcoin client with different rules", and I don't. Difficult? Absolutely. Darn near impossible? Yup. Do I think it will ever happen? Nope? Am I a firm believer in the mathematics of Bitcoin, yup.
But, impossible? Nope. In fact, I don't even believe it needs to be "everyone". But for the sake of argument, say everyone. I believe that it would be possible through legislation, port blocking, and other evil tricks (both technological and political / legal) for the governments of the world to render the current Bitcoin client useless. I think you are kidding yourself if you think otherwise.
Or without even convincing ANYONE to "use a different client", if a major entity / government created a new block chain with a higher difficulty level, diverting all the mined bitcoins since the last check point to them, and then performed a worldwide Black Out, to knock out the internet and Bitcoin, and when worldwide power got restored one city at a time, and one-by-one, as people were connecting to the internet, and discovering a new block chain with a higher difficulty, they'd reject their existing block chain dating back to the last check point, and boom, the deed would be done - tons of transactions reversed. Do I think this will happen? Nope. Do I think it is
possible? absolutely.
In fact, I think that it is still very much within the realm of the budget of the US Government to undo a day's worth of transactions, and probably many more.
Don't get me wrong, I have a ton invested in the success of Bitcoin. I just believe that you lose credibility when you toss around words like impossible and mathematical certainty, when they fall just short of that 100% number. 99.9% with 300 9's after the decimal ISN'T 100%. Sorry.
We should probably agree to disagree on this one. I like your document, but I am just trying to explain my reaction. It's your document - you asked for feedback, I didn't mean any offense. Just providing feedback, and trying to explain what I meant.