Quote from Soon2Bgreat:
If you vol weight it you'll have large FI exposure, not good if rates go up.

Quote from atticus:
You need to add some optionality/convexity to a passive portfolio construction if you want to beat the S&P; whether it be some ratio overwriting, simple CC or some sort of leveraged-ETF arbitrage. Beta is pointless as you'll be constantly tinkering and who says it will beat?