ΔE 11.5, fair: the same colour family, but not a straight swap. Thousand Sons Blue is noticeably darker, more muted than Mediterranean Blue.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Thousand Sons Blue is noticeably darker, more muted than Mediterranean Blue.
The same difference applies the other way round: Mediterranean Blue is noticeably lighter, more saturated.
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 Mediterranean Blue on the colour wheel See Thousand Sons Blue on the colour wheel
All matches: Mediterranean Blue equivalents · Thousand Sons Blue equivalents