I woul accept a system that invest only in TIPS. But corporate America is yielding internal rates of returns, on the average that are twice what long term bonds do, so a mixture of the three ETF and TIPS would be a ood long term chpoice, provided no timing exercise are allowed. Even if the market goes nowhere like in the 1966/82 period and the current 2000 to ?, monthly investments of same amounts would eventually yield more than treasuries.