Ive sprayed many gallons of OMNI in basecoat and in SS. Omni will take more coats to yield the same amount of coverage, sometimes the added product in Omni will cost the same as the DBC.
Omni black is a dirty brown black not as clean deep looking as DBC. Doesn't matter how you tint Omni it will be dirty in appearance.
If you want a good deep black Id look into SPI.
https://www.southernpolyurethanes.com/