With regards to the utopian society you are mentioning, what checks and balances do you see there to be to prevent some outside power from coming in and conquering these small scale coops?
Personally, I do believe mixed-market capitalism is sustainable and moral.
In terms of the class divide that comes from capitalism, I personally am a fan of that divide, as it is in constant fluctuation. In theory, with enough innovation and hard work, anyone can become a member of the upper class. Additionally, with enough poor judgement and poor spending, anyone can end up falling into the lower class.
I find it moral because capitalism is what I see as the closest thing to a meritocracy, whereof those who can effectively work will succeed, and those who cannot will not.