Not sure about whether the frequency charts fully addresses the issue. Notes of the same pitch higher up on the D string were still much louder on my stingray (apologies if this misses the point).
I could mitigate the quiet G string issue by adjusting the eq (removing the scoop), but as that left me with a tone I didn't want it was pointless.
Five years after my bad experience with a Stingray, I have recently purchased a five String EBMM Sterling. Hope this will be ok, but obviously I'm yet to play it in anger...