On the other hand, choosing Capitalism seems to be an irreversable decision, too. I'm not sure exactly what your argument is here.

Choosing Capitalism is quite reversible. In America, if we decided communism was a good thing, we could all vote for communist senators, representatives, governors, and even a communist President. From the inside, they could change the American political system in such a way that it no longer was a democracy full of communists, but a true communist government. Now, once that's done, because communism has historically relied on iron-fist dictatorship, with no chance for people to affect change, it's irreversible, without some kind of hostile rebellion amongst the populace.

No?

And there are as many non-Communist tyrannies as there are Communist tyrannies (without actually counting).

That's like going to your local grocery store and saying there are as many rotten apples as there are rotten kumquats. It's true, but only because there are a thousand apples and only 30 or 40 kumquats.

The fact is, percentage wise, it's not even close. And to try to say that most or all communist dictatorships are only dictatorships because of foreign intervention (what you seem to be saying) is a real stretch.