My point isn't that I think people should never read anything by Heinrich or anything, nor that I am arguing for purity. I think Heinrich presents a very specific reading of Marx that lends itself to opposing practical action with respect to existing socialist states, and that this insistence on adhering to Marx and minimizing the contributions of Engels downplays Marx's lifelong agency and cowork with Engels. Harvey is more agnostic, in that sense, and defends the Fowkes translation, based more on the French edition that Marx developed latest than earlier Marx-only editions.
Really, this gets more into esoteric and usually trivial differences. Among modern Marxist economists, I am most a fan of Ian Paul Wright over others.