My observation was with one somewhat failed PCV valve, more air was forced in into the intake from the crankcase via the PCV, probably producing more power; it definitely increased fuel consumption. Given that it is venturi tubing/piping from the pcv this increases airflow disproportionately in relation to the diameter of the tubes and different passages in the upper intake (I assume). Installing the new PCV valve also definitely decreased oil consumption.
I have no proof, but in principle should want all unclean mixtures out of the crankcase asap and the vacuum is certainly strong.
If it runs just like with two new PCV valves, should be as good except any potential benefit of blow by being combusted (potential lubrication) not happening.