ΔE 11.6, fair: the same colour family, but not a straight swap. Middle Stone is a little darker, more muted, warmer than Pestilent Flesh.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Middle Stone is a little darker, more muted, warmer than Pestilent Flesh.
The same difference applies the other way round: Pestilent Flesh is a little lighter, more saturated, cooler.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Pestilent Flesh on the colour wheel See Middle Stone on the colour wheel
All matches: Pestilent Flesh equivalents · Middle Stone equivalents