My argument isn't necessarily an economic one. I don't particularly think that a high estate tax will stimulate the economy, but I also don't think it will hurt

My argument isn't necessarily an economic one. I don't particularly think that a high estate tax will stimulate the economy, but I also don't think it will hurt. The advantage of a high estate tax is more a social one of removing unearned wealth and freeing up some money to spend on social programs. But you're right that it might be more efficient to make the tax 95% so the beneficiary has an incentive to handle the liquidation so they can get their 5%.