ΔE 12.9, fair: the same colour family, but not a straight swap. Speed Metal is noticeably darker, more saturated than Runefang Steel.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Speed Metal is noticeably darker, more saturated than Runefang Steel.
The same difference applies the other way round: Runefang Steel is noticeably lighter, more muted.
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 Runefang Steel on the colour wheel See Speed Metal on the colour wheel
All matches: Runefang Steel equivalents · Speed Metal equivalents