Looking at how someone votes when things aren't close won't tell you much about their conservative integrity. RINOs will usually vote with the party when their vote doesn't matter. The question is whether they will do so when it does.
The discussion of Specter has got absolutely nothing to do with "conservative integrity." It just comes down to votes. Those judiciary committee votes were all 10-8. Specter winning in PA over the DEM helped preserve the GOP majority, which is why they have two more members on the judiciary committee than the DEMs have. That's all there is to it. If the GOP loses the majority, it's 10 DEMs to 8 GOPers. No Roberts, No Alito, No Nothing. This isn't an integrity contest; It's politics.