Is the opportunity to convert IRAs to Roths irresistible?

If you have the cash, my conclusion is that it IS an irresistible idea.
Starting January of this year, everyone has the opportunity to convert existing IRAs to Roth IRAs by declaring the intention and undertaking to pay taxes on the amount converted at the income rate for this year ( there is also the option to have half taken as income this year and half taken as income next year, when the rates will presumably be higher.) Based on the present understanding, once the taxes are paid on the current amount at the current rate, the contents of Roth IRAs thereafter are exempt from taxes meaning both the current value as well as any increase in the future. There would also be total tax-free freedom to withdraw the contents at any time or not. Further, any Roth IRA would have the same tax-free aspects for inheritors ( although the amounts would be subject to estate tax at the time of transfer from a decedent.)
Considering that the Bush tax cuts will expire at the end of 2010, that there will be a 3.8% tax surcharge mandated by the Obamacare bill and that the Obama administration has threatened to raise taxes in other ways for taxpayers whose gross incomes are > $200K per year, the arithmetic would seem to favor conversion except for two factors: 1) the time value of the taxes paid this year compared to stretching them out over the statistical lifetime of the holder of the ordinary IRA and 2) the risk that the government will violate the spirit of what a Roth IRA is and try to tax the already-taxed Roth accounts yet again.
If one takes the Obama administration-- with a Democratic Congressional majority-- at its word ( not necessarily a slam-dunk, of course ), there will be a division in the tax rates based on a line at $200K/ per year. For retirees, it might be possible, by prepaying taxes on all IRAs in the conversion process, to lower their income from residual assets not in IRAs to be less than $200K/ year reducing the MARGINAL tax rate enormously.
The tax code is impossibly complicated and full of pitfalls but also loopholes. Here is one available to the "average" ( if upper-middle-class) person. Prepaying the tax on conversion also reduces the amount subject to estate tax. A Roth can be left to children and grandchildren,left to earn tax-free and can be distributed tax-free. The only required minimum distribution is based on the life expectancy of young or very young children, only a couple of percent a year so the Roth will increase in value over time on a tax-free basis.