New Test. Try this out yourself!
I have a 1080/8bit Uncompressed QT of 75% bars.
I import into FCP. Put into 8 bit uncompressed 1080 sequence. Bars check out against scopes.
I import into AE. Put in timeline. Bars check against Color Finesse scopes. Working space in AE = 709. Assigned profile on QT comes up as 709. output module is rendering with 709. Color Finesse scopes set to 709.
Render 8 bit 1080 QT from AE. Import into FCP. COLORS and GAMMA SHIFT.
Bring that rendered file back into AE, check against orignal bars, it IS PERFECT.
So it seems that Final Cut is completely mi-interpreting these quicktimes rendered by AE?