i've seen it done 2 times
once was the same color to 'restore' the case, i did it on a 1x2 smooth black. Looked good.
other was some doing a 2x4 a different color... looked 'ok' but i think the case lost some 'class' by the look... it was also smooth leather.
I wouldn't recommend it.....
no prep was needed...
i definitely wouldn't do a textured leather
one coat wasn't sufficient
no it didn't scratch easy- it isn't paint, it's a dye.
it just doesn't look 'right' when it's done...
just my .02...........trying to help...