That's not even part of the question. The question boils down to which is better: A small aristocracy with all the money or a huge middle class with all the money?
It's a simple question. If you own stock in or are working at a manufacturing plant that depends on selling X number of units per month to keep the lights and machines on, which would you rather have as a market, 6000 Aristocrats with a few billion in the bank each or 7 billion people with middle class incomes?
Should that answer be different for Europe? For India? For America?
But the question isn't that simple Joe because a free market economy where human rights are respected needs both. China is neither a free market economy, though they are embracing some captialism now as they recognize its benefits, nor do they respect basic human rights as unalienable rights.
So all other things being unchanged, of course China would prosper if all its citizens were middle class. But the fact is, without the rich PLUS a free market economy and basic human rights, no middle class is possible. There will only be rich and poor.