Great information guys. I was thinking of selling my 18 Behringer Sub and buying the JBL SRX 828SP. Should be a good combination for the power.
FWIW, I've been doing outdoor shows with (1) 815p over (1) 818p per side. It works fine at not super loud concert levels, which is what the client wants. I run the system wide open with the tops turned down a bit and the subs at max. The limiters engage at times. I do not ever hear any distortion nor is there any smell. The system works beautifully and can be transported along with 5 monitors in my minivan.
I do want to double my sub's once I have a means to transport them, but the system works nicely as it is for crowds of up to 1000 in the park. The music is local classic rock or tribute bands, no EDM or hip-hop.