Aren't they always?Dispersion, which with that rig is pretty narrow above 800 Hz. OTOH since dispersion is the only benefit from running into the PA pull the bass EQ on that channel strip down, and run a mic'd send, not DI, to capture the midrange tone of the speaker and spread it through the room at a level just loud enough to fill those areas where the backline can't. An intelligent FOH guy who understands what you're trying to do will likely be the limiting factor.
Bassmec, I'd say those 3 SVT cabs on stage right in that picture of the line array you posted would do a pretty good job of keeping up, but in a arena, I'd mic and run through the PA anyway
