I am struggling to see any recent post regarding this book and have been exploring the topic for about 6 months now. I saw a post about it in r/bogleheads about 2 years ago, so I wanted to bring it up again. If anyone here is implementing the strategy themselves, I'm curious if you are taking into account the Shiller PE ratio. Per the book, you do end up with higher returns when taking it into account when leveraging your investments, however for the last 10 years the Shiller PE ratio has been > or equal to 27. Per the excel sheet calculator on their website this would mean that your Samuelson Share is 0% which would equate to having 0% investing into the S&P500? Either I'm looking at this wrong or following their advice would have led to you missing out on one of the biggest bull markets in history. If you don't take into account the Shiller PE ratio, for the current VIX of 29%, you would be investing 22% of your Present Value of Future Savings.
Some things to note is historically, the Shiller PE ratio has never (since 1871) been consecutively this high and the book was written in 2008, so they were working with environments that are not reflective of today's scene.