Robert, I agree with most of what you wrote, but I wanted to post something in response to this sentence:

Another problem is that it appears the levy will be placed on firms without sufficient discrimination based on different kinds of risk.

This raises the question of who would be in charge of assessing risk. I wouldn’t want it to be the federal government (or the federally sanctioned rating agencies). For one thing, based on its track record, the government would do a terrible job. (cf. Barney Frank in 2003: “I do not want the same kind of focus on safety and soundness [with regard to Fannie and Freddie]. . . . I want to roll the dice a little bit more in this situation towards subsidized housing.”) For another, it would create an incentive for banks to minimize their tax liability by overloading their balance sheets with whatever instruments are classified as “least risky.” This very incentive structure contributed to the severity of the current crisis. (Apologies if I misunderstood you and this is not what you meant.)