So 6 subs still centered in front with 835 on stand?
Centered and spaced, and whatever you need to get the top boxes up. Or pile the subs L/R. I'm not out to kill power alley and sub deployment is more about the placement options that are NOT available than anything else (at least for me, others may have more OCD tendencies).
The reason I seldom center subs: many of the artists I work with do not like the amount of LF that placement puts on the stage... as in "fix this, I'll be in my dressing room when you get your shit together." For rap shows, it's about the way the subs interact with the sidefill subs (make an LF hole in the middle of the stage and the rapper will not be happy).
But for the BE whose Daily Don Quixote exercise is to banish power alley, I'll center the subs as the BE is aware of the stage LF and the artist is presumably okay with it.