John Buckley (Chief Democratic Tax Counsel, House Ways and Means Committee) has published Estate Tax Repeal: More Losers Than Winners, 106 Tax Notes 833 (2005), also available on the Tax Analysts web site as Doc 2005-2468, 2005 TNT 30-17. Here is the Conclusion:

The uncertainty facing estate tax planners is large because there is a wide range of potential outcomes to the debate on estate and gift taxes. The current system could be retained, but with substantial changes. Congress might simply extend the law in effect in 2009. It is conceivable that the budget pressures may force Congress to freeze the phase-in of the existing estate tax reductions at levels below what they would reach in 2009. Finally, Congress could extend the repeal.

Estate tax planners who base their estate tax plans on repeal must understand that repeal will benefit an extraordinarily small number of estates. Even many of the 7,500 estates that would have estate tax liability with the 2009 exemption level would face tax increases because the potential capital gains taxes from carryover basis could exceed their estate tax liability. In contrast, the new carryover basis rules will impose substantial compliance burdens on more than 71,000 estates per year. A significant number of those estates also will suffer tax increases from carryover basis, even though they would receive no benefit from repeal.

For the overwhelming percentage of estates (in excess of 99 percent), a simple extension of the law in effect during 2009 would be the optimum result. They would continue to enjoy full step-up in basis, and have neither estate tax liability nor any return requirement. The only question is whether their best interests will prevail in the congressional debate.