Ah, talking about more complex portfolios than the basic two-component default portfolios, one can play with the more sophisticated options in FIRECalc, and get some better results.
Caveat: I do not know how FIRECalc exactly defines US small cap, small cap value, etc..., and also where the author obtained historical performance values. Also, we do not know how well future performance can be predicted from the past.
If I had access to the FIRECalc computation engine, I could wrap an optimizer around it, and write an optimization program based on the common Simplex algorithm. But as I can only play with FIRECalc by varying manual inputs, I can obtain a better portfolio than the simple 2-component portfolio, but cannot claim it to be the globally optimal (meaning the solution I present may be simply a local maxima).
Before we claim something is better, we must define "goodness". Following in the OP's spirit, I will say that portfolio A is better than portfolio B if A allows a higher WR rate during a 30-year retirement period, while also not drawing the portfolio below a certain threshold, such as 40% or 50% of initial portfolio value,
With that definition, I have found that the following portfolio using FIRECalc model is superior to the simplistic 2-component portfolios.
NW-Bound Optimal Portfolio
US Microcap: 6%
US Small Cap: 6%
US Small Cap Value: 6%
US Large Cap Value: 6%
S&P 500: 16%
US Long-term Treasury: 0%
US Long-term Corporate Bond: 0%
US 1-month Treasury: 60%
Note that the above portfolio is 40% in US equities with an emphasis on small stocks, and the rest of 60% in short-term fixed income almost like cash!
If you take the 40% equity simplistic portfolio, using a $1M initial value and a WR of $30,791 (see my post #20 above), you will get this following FIRECalc result.
The lowest and highest portfolio balance throughout your retirement was $400,930 to $4,944,019, with an average of $1,454,631. (Note: values are in terms of the dollars as of the beginning of the retirement period for each cycle.)
That $400,930 is the minimum value that we desire.
Now, keeping the same WR of $30,791, and use the more complex portfolio as I describe above, you will get
The lowest and highest portfolio balance throughout your retirement was $619,352 to $3,054,433, with an average of $1,448,184.
Note that the 2nd portfolio brings up the minimum, while reducing the maximum such that the average value is the same. In other words, the more complex portfolio has less volatility, and provides the same average return.
All that for 60% in almost cash! Can you believe that?
PS. Alternatively, if you can settle for $400K minimum portfolio value instead of the $619K above, you can draw $33,081 instead of $30,791. Resultant FIRECalc summary follows.
The lowest and highest portfolio balance throughout your retirement was $464,486 to $2,868,181, with an average of $1,296,244.
Note that the worst case end balance is $464K, but the lowest point in the 30-year period is $400K, meaning that it bounces back.