ΔE 15.3, loose: different enough that you should pick on purpose. Dark Reaper is a little darker, more saturated than Hell Bent for Leather.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Dark Reaper is a little darker, more saturated than Hell Bent for Leather.
The same difference applies the other way round: Hell Bent for Leather is a little 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 Hell Bent for Leather on the colour wheel See Dark Reaper on the colour wheel
All matches: Hell Bent for Leather equivalents · Dark Reaper equivalents