^^ 87% of all global equities that went up 1000% or more over the past ten years were microcaps^^

You really need to know the proportion of microcaps that rose 1000% within the microcap universe, rather than all stocks universe, because most of the listed firms are microcaps, so this stat will be just a result of population. Similar 87% of all global equities that start with A might be microcaps, so you need to check the proportion of any characteristic from its own microcap population, to draw conclusions about microcaps.

There are about 4,300 exchange listed microcaps under $300 million.

On the other hand.. In the Compustat Database back to 1951 James O’Shaunessey did find that the very smallest micro caps under $25 million really massively outperformed at a 25+ CAGR .. but he believed the huge spreads would more than destroy the outperformance. It would be good to check his result but I expect he is right (unless your capital is just a few thousand and you can hand the low volume). Note :— the outperformance of small firms was heavily skewed to those really really small under $25 mil.