I'm one of those who only use subs to extend the PA range downward. Most people use them to add stupid amounts of excessive bass. If the drummer really wanted to sound like that, wouldn't they bring their own rig??. We will never be on the same side of that argument. The DriveRack PA makes my type of use easy. Not sure it works as well for that other.
Having subs on an aux send doesn't change the balance of a given system unless you want it to. Setup by the book, aux sub system response will be identical to a "standard" setup with subs treated like a regular bandpass on a multi-way crossover. The advantages of aux subs are:
1. keeping low frequency "gak" out of the subs from open mic sources that cannot be completely eliminated by high pass filter which in turn...
2. saves subwoofer headroom by not reproducing low frequency information from mics you don't want in the subs anyway
The more open mics you have on a standard system, the more aggregate low frequency information gets into the subs.
With aux fed subs, only the sources that need subwoofer reproduction are sent to the subs. Nothing else. This tends to increase system clarity and headroom. On big systems where you have a lot of PA and a lot sub, it's almost essential in my opinion because vocal mic plosives getting into the subs can sound tremendous. Aux based subs fix that issue without having to resort to drastic high passing of the offending channel that can suck the warmth out of the vocal tone because the plosive can't reach the subs.
But by all means, do what works for you. But don't assume that folks running aux subs are in it just to overwhelm you with subwoofers. They may be doing it for the exact opposite reason.