I personally am not a fan of throttle to rudder mixing, far to complicated to properly setup to use in all speed/throttle combination's IMO. Even with electric I don't think its required, and proper trimming/thrust adjustment will get you there. That includes any addition of left rudder at low throttle, never felt or saw the need for it.

On my Integrals I only run two mixes, rudder to aileron which is a flaw in amount of dihedral in the wings, and couple % of low throttle to down elevator for downlines. I run no other mixes on that model.

I think one thing overlooked (or maybe I just missed it) in all this is downthrust. No matter what your wing incidence and CG is, if your downthrust is not correct the 1/2 positive in the wings/forward CG will likely result in upline issues. 1/2 deg down or less seems to work well.