I would concur with Jim that the number of brackets in itself is not a crucial concern for policy. As I said in my presentation, I think that the threshold for the top rate should be higher, but I do not necessarily think that the top rate of 29% is excessive in terms of either incentives or in comparison with other countries.
I think some issues of high marginal tax rates on upper earners really come out of the provinces--Ontario in particular, with its rate schedule and surtaxes labelled as, whatever, a health care tax. The provinces are the places to look for flattening of rate schedules. The progressivity in the federal rate schedule is appropriate. If you want progressivity in a tax system, as many people do, it should be at the federal level much more than at the provincial level.