The book was written in 2007 when not even the most zealous optimist is willing to say that real estate will appreciate in the short term. The authors advise you to leverage your money so that you can invest in a stagnant or falling asset?
Furthermore, there is little hope that interest rates will do anything but go up in the near term. Certainly, if you can make more on the bank’s money than your after-tax cost of borrowing it then paying off your mortgage early doesn’t make sense. I just don’t see how that can be done in this RE climate.
In this market, not borrowing at all seems to make the most sense. Why not rent and invest the money you save not paying interest, taxes and HOA’s. Hopefully the recent tightening in lending practices will prevent the “undisciplined spendthrifts” from attempting to implement the author’s dubious advice.