I agree with this, partly. With those nice PA subs you're going to have all the lows you need, because they're omnidirectional. It's the mids and highs that you're going to need on stage and you may not get enough of those from the existing monitors.
I figured the horn on/off switch on the 410 and 115 would get used frequently for that purpose. I was also gonna utilize my MarkBass "SuperBooster" pedal with all of this beastly bass-stuff to help to further improve the quality and balance.