Ah, that's exciting. The drivers being essentially sonically the same (as long as the magnets are the same) means a lot for some mods I'm trying out.
Some conclusions I've made.
1. THX00 and EMU drivers are sonically similar with out the cups in both measurements and by ear.
2. With cups they reveal their magnet tuning. Ebony cups in Emu makes them sound like THX00 but ebony cups on THX00 make them sound bossier with smoother highs. Teak cups on the THX00 brings forward the mids and retains similar baas but on the EMU is makes them very natural sounding and smoother across the sound spectrum. Which also matches with my measurements.
3. I gotta test out TH600 pads, ZMF, Alpha Pads, HM5 pads on my headphones to measure the differences. Too poor right now since I got a lathe to learn wood turning to test out differenthe wood cups. But you've confirmed that pads can make quite the difference within the same driver magnet tuning.