Bernstein isn't sure where the political advantage lies:
[As a Republican candidate for president, would] you rather risk being attacked for going along with the Obama tax boondoggle that raised the estate tax along with all sorts of new wasteful spending and pork...or would you rather risk being attack for voting for The World's Biggest Tax Increase?
You might think that one can examine the bill itself and some set of principles to determine the proper conservative position. If so, you would be wrong. For the relevant value of "conservative" (sorry, Andrew Sullivan), what matters here is what movement conservatives will believe going forward. That's especially true on something like this, in which there's no obvious reason to believe or way to prove that either a yes or no vote is in favor of lower taxes.