Thanks for your thoughts. Is it possible to use your data to identify how many rolling time periods there have been since 1930 where the years of outperformance of cap weight over equal weight for the S&P500 exceeded our current stretch? I'm curious how rare it has been historically for the period of cap weight outperformance to last as long as this.

Sure.
I looked at rolling five year intervals, real total returns, annualized, of both strategies. My tables haven't been updated in a while, so they end last April at the moment. But for a test of over 90 years a few months shouldn't matter much.

Percentiles of the difference, positive numbers meaning equal weight did better.

0.00    -8.98%
0.10    -2.70%
0.20    -1.50%
0.30    -0.31%
0.40     0.73%
0.50     1.54%  median advantage rolling five year interval
0.60     2.42%
0.70     3.82%
0.80     5.23%
0.90     7.87%
1.00    24.98%

Simple average across daily starts of the five year advantage: 2.16%/year
Probability of equal weight having the advantage in a five year stretch: 66.54%

Some of this is probably overly optimistic, as during many of those years it was hard to do equal weight and less hard to do cap weight.

Same percentiles of the gap again, but only the figures since 1960

0.00    -8.98%
0.10    -2.30%
0.20    -0.97%
0.30    -0.12%
0.40     0.70%
0.50     1.41%
0.60     1.99%
0.70     2.96%
0.80     4.61%
0.90     5.74%
1.00    11.09%

Simple average across daily starts of the five year advantage: 1.55%/year
Probability of equal weight having the advantage in a five year stretch: 68.49%

...and lastly, just the figures since RSP was launched in May 2003

0.00    -4.58%
0.10    -2.58%
0.20    -1.73%
0.30    -0.89%
0.40     0.11%
0.50     0.93%
0.60     1.72%
0.70     2.38%
0.80     4.34%
0.90     6.63%
1.00    11.09%

Simple average across daily starts of the five year advantage: 1.38%/year
Probability of equal weight having the advantage in a five year stretch: 60.68%

Please don't ask follow up questions - I just calculated all the five year rolling figures for this post, then threw them away : )

Jim