Mixed dyes with 1-4 colors use the same dye-palette as new dyes. the dye pallete of these got updated too.
it will look exactly the same...
i have over 60 mixed dyes, so i know
however, u can use 2 or more mixed dyes at the same time to make mixes of 5-16 colors.
but mostly it looks crap or u dont see a diffrence...
another exeption are dyes with dye remover, not sure bout these.
facit: dont use mixed dyes, it would be a waste^^