for me, the sound signature of the drivers don't matter as much as how indistinguishable they are from each other, because we have a pair of ears precision and consistency counts for more than flavour and signature
I have been using Equalizer APO daily with these settings on my ER3-XR where the driver on the left side has excessive bass response, I listen to bass heavy music all the time and not even the ER4 channel matching goes below 100hz... Individually the drivers sound flawless, but mismatch in the low frequency region produces a very unnatural and almost nauseating effect