I highly recommend Robert Murphy's insightful evaluation of Murray Rothbard's <em>Man, Economy, and State</em> on the 50th anniversary of its publication.
Even if they differed on the similarity of the social and physical sciences, it does not follow that Mises and Menger differed on the correct method of economics.
Marx's devotion to communism was his crucial point, far more central than the dialectic, the class struggle, the theory of surplus value, and all the rest.