Show me the numbers that show it is inferior
Using SCORE comparisons, KO preferred matches up with HiLo I18+Fab4 in just about every playing condition, even without a true count conversion. Splitting 10's is not in KO preferred, so if you don't do that, it will almost always outperform HiLo.
... and it's a lot easier.
PS: The ReKO version of KO is even easier and is about 99% effective as KO.