AAI

Money Magazine ETF Recommendations: Keeping It Simple May Be Stupid

Some of the other "asset classes" you mentioned are highly correlated with the five highlighted by Money magazine, which puts you FURTHER away from your efficiency frontier because of expenses and taxes as investors try frantically to re-balance such an over-diversified portfolio quarterly or semi-annually. I strongly recommend you take a look at David Swensen's "Unconventional Success: A Fundamental Approach to Personal Investment." Swensen is one of the world's most successful investors, whose arguments you don't address at all.