Theory -and then -practical application:
On a model -best set em equally -if they are same size.
Why?
The model will fly BEST- when the total drag of the two wings is minimized. both exactly the same
At what AOA do you think your model will be in level cruise?
If it is light -I will bet it is under one degree ( that is about 1/4" in one foot)
Of what good will it be to create a drag brake by setting an angle DIFFERENCE, greater than the AOA needed to fly?
Much research on bipes was done on slow , heavy, full scale stuff .
Totally different ball game than our models -unless you like really heavy models .
When w e did fully aerobatic bipe models (TOC 89-91)-we found best setup was always 0-0-0.
then have enough power to maintain speed .
If speed is constant -- trim remains the same
If speed changes dramatically with any change in pitch -due to low power well-- that's another story.