Good for comparing one stereo pair against the other, but less likely to be less useful for mixing all four together than alternate configurations if that's what you're more interested in doing. Not saying it won't work to do that, only that other configs are likely to work better for doing that.
If the goal is a config where all four are intended to be mixed them together, you ideally need a lot more spacing/angle difference between the two pairs so that each pair is contributing something different, instead of just stepping on each other's toes, smearing things. Quite wide spaced PAS with X/Y in the middle is good that way. PAS in the middle plus a really wide angled outside pair (like pointing directly sideways- don't laugh until you try it) can be useful. One useful thing to try, which may sound radical, would be to use a center PAS supercard pair to isolate the direct PA sound as much as possible, and point a wider spaced cardioid pair in directly the opposite direction, fully away from the stacks so they are in the null of the cardioid pattern. That gives you maximum separation between the direct sound element in the PAS pair and the reverberant/ambient/audience element in the other, and should provide the most flexibility in finding the most optimal balance between those critically important aspects when you mix them together.
If both pairs have pretty much the same information in them, you don't end up with very much flexibility at mix time, it either sounds better than either pair alone or it doesn't. When they contain very different parts of the "total sound" you gain more mixing control because the two pairs don't overlap and compete with each other. Each pair brings their own contribution to the party. If everyone brings mac & cheese to the potluck dinner, the meal options are going to be pretty boring without much variety, even if each dish is prepared a bit differently. Its much more interesting if everyone brings something different, and allows for much more choice in the particular balance of what each person ends up with on their plate.