ORIGINAL: seanreit
My experiance is whatever down you need for inverted flight in a swept wing airplane is just that, what you need. I have seen no real information or proof that how well my airplane flies upside down without stick input has anything to do with my CG.
I did notice on my lightning that barely any input was needed, but as mentioned above, it is basically a straight wing airplane.
any dihedral or anhedral in the wing/stab/canards all play a roll on trim change in inverted flight so unless you have a perfectly flat (no dihedral/anhedral) wing/stab you're gonna get a trim change even with perfect CG