I'd attribute your ProAc dealer's remarks to the fact that he's a ProAc dealer.
IME, properly set up subs are a revelation. Of course, that part about properly set up is important. Few full range speakers can produce clean measured response in the deep bass ala Rythmik, JL, SVS. Further, properly placed subs will create much smoother bass response, although this can also be achieved with room correction like Audyssey.
Either way, uncorrected bass response from a floor stander out in the room just doesn't cut it for me anymore.
Marty
IME, properly set up subs are a revelation. Of course, that part about properly set up is important. Few full range speakers can produce clean measured response in the deep bass ala Rythmik, JL, SVS. Further, properly placed subs will create much smoother bass response, although this can also be achieved with room correction like Audyssey.
Either way, uncorrected bass response from a floor stander out in the room just doesn't cut it for me anymore.
Marty