Ok, so my experience with the old WOW inks versus the C3 system:
You HAVE to go to a heavier pigment load in order to achieve the same opacity. So you will always use their HO formulas. Also flashing a C3 formula is slower and depending, the after flash tack is a bit longer. This is alllllll because mixing system inks are not finished inks. With finished inks you have more room (chemically) to improve that individual color's performance, flash, opacity, etc... You will still see yourself needing to strategically flash.
With that said, I like their system. We use the V.O. base (Very Opaque). It has a "grey" component to it that helps with blocking some light. Works very well wet on wet. High color count wet on wet printing over a white base you might see some ink "drying/flashing" issues with colors early in the sequence. We were told to add 1% plasticiser to those colors to help with that.... hit and miss imo....
You will never be able to match the XOLB performance with a mixing system. Each ink is specially formulated for that color and for the XOLB properties. So you may find yourself still stocking the XOLB inks.
I do love the flexibility of a Pigment/Color Booster mixing system. You will find yourself offering a lot more as a result of the different bases and the flexibility of the color boosters.