Anarchism wouldn't' make any difference. The rich and powerful will still have the men with guns.
And the poor, who are by definition more numerous than even the praetorian class, will also have guns. If it comes to a shooting war... well, there's a reason kings don't have a lot of power anymore. 
Just like there can never be a millionaires party, there can never be a praetorian party.
But Marx was wrong - they don't operate as a single class. They bicker and dispute and form political movements and the poor split as well. The disadvantage of anarchy is that guns are the only way to settle these disputes. Democracy is a nicer way of doing things even if your particular idea will never be voted for.