I have been a painter for over 20 years. When it comes to dark colors covering- the paint has nothing to do with it. To get a paint dark red you have to start with a base that has little to no pigment initially. Dark reds require 14-16 ounces of universal pigment to acheive the color. Regardless of the brand they all rely on the same universal colorants. So they all cover the same. RL paint uses the same colorants as Behr, Ben Moore, P&L etc. These Paints would dry pretty clear without the added pigment. Lighter color bases are already tinted from the factory with higher hiding pigments like titanium dioxcide, calcined clay and calcium corbonate. If you added 15 ounces of colorant to a pigmented base you would overflow the can and never achieve the deep colors. Tint a primer (it's less expensive than the paint, and do a coat or two over it.) Or tint the primer gray. Why do you think automobile primer is Gray.