>if the end result is rising incomes for all, better life expectancy and an overall better quality of life does it matter that it came about through an authoritarian regime?

And when this growth ends, what will happen? An authoritarian system is able to withstand challenges with the full power of the state behind it. People that dissent are crushed, and many times the people that dissent do so with the most honourable of intentions. Viewed under the prism of authoritarianism this matters not. It's a system that remains not because of consent and merit, but ultimately due to suppression of dissent.

Just because China is able to catch-up some of the growth that it completely missed out on due to the turmoil of the Communist revolution and the turbulent 50s and 60s, doesn't validate this system one bit. Other countries were ahead of China, with more growth and sustainability, minus the cruelty.