I've seen a few bands use it where everyone is going direct (even guitard) into that system. Both people using POD XT Live or comparable Boss units. Sounds ok for what they were doing, but it was mostly the tired 60s/70s/80s tunes all in the same few keys, so it wasn't authentic to the tunes anyways. You could hear the bass ok only b/c it was just a 3 piece and the drums were just acoustic and not mic'd except for the kick. This same band plays at my fave bar so I always walk by and check it out.
It works for them, but for a loud rock band, I'd think you'd need a LOT of those things and twice as many Sub pieces/engines, so just depends on what style you play. They're light and sound good, but whew are they high ($$). Worst thing you can do is test it out and go from there.
When I played in a country cover band we were going "All PA" except I had my rig that was barely on and the lead guitard had a little Peavey 112 combo that was barely on. Course that was like a 10,000 QSC+JBL rig that was just stupid huge and loud, so it sounded great!