There is a
world of differences between mics. It's not about “color”. It's about the circuitry. With a U87 in a good room, you probably won't
need any EQ.
I don't doubt that for a second.
I'm just speaking about using microphone
emulators, not the "real thing".
If you're using software to emulate a U87 (for example), that software isn't going to be able to take the signal and suddenly make sounds that didn't exist suddenly appear.
At best, it's probably going map the frequency response curve of your microphone onto that of a U87.
That's essentially using an EQ to color the sound, right?
It may be that the microphone emulator is a lot more sophisticated than that, and emulate the circuitry of each microphone... Nah.