IDF Modern Grey vs Hobgrot Hide

How close are they?

ΔE 9.4, close: similar, with a visible difference side by side. Hobgrot Hide is a little lighter, warmer than IDF Modern Grey.

Can I use Hobgrot Hide instead of IDF Modern Grey?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Hobgrot Hide is a little lighter, warmer than IDF Modern Grey.

Can I use IDF Modern Grey instead of Hobgrot Hide?

The same difference applies the other way round: IDF Modern Grey is a little darker, 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.