In previous threads this community concluded that pack SoC swings reduce pack life, and that the MT encourages swings more than the CVT does.
This is important to me because my commute is up a ~7 mile rolling hill, typically the pack goes to 30% SoC into work, and back to 100% on the way home. I have been riding the pack up the hill in 5th gear.
In a previous thread someone commented that the CVT allows the engine to rev fairly freely when the accellerator pedal is pressed, which seems to spare the pack. I have have also seen the IMA more willing to assist at lower rpms than higher ones.
So I tried to emulate the CVT into work today by downshifting on the uphill grades, once I was in third at about 45 miles per hour, and most of the climb was in fourth at about 50-55 miles per hour. The IMA did kick in a bit, but the pack didn't go below 70% SoC.
Overall mpg was down about 1 mpg (37.8).

Not bad at all!
I am thinking the ICE is more efficient at the loads and rpms I used, thus making up for most of the loss of IMA.