Well, just for the record, I am an admirer of von Mises, as well as Rand.
There's nothing wrong with a pragmatic indictment of Communism, per se. The trouble is that the pragmatic argument fails if they manage to hold things together (Mainland China comes to mind). Rand, OTOH, provides a powerful moral argument against Communism (or any form of totalitarianism) that is immune to the vulnerabilities of the pragmatic argument.
On balance, I think there's a great deal we can learn from both Rand AND von Mises.
So would Rand support a "free"(not) trade with communist china?