Well the room is the key, and you seem to know it better than I do. I do know that I have heard the Mahler's sound incredible, and yes, better than the Beethven's. However, I've also heard the Mahler's sound terrible in rooms to small to handle them. Bass bloat that will drown out the music.
So I would say that if he is comfortable that he can tame all of those woofers, he is welcome to try it.
So I would say that if he is comfortable that he can tame all of those woofers, he is welcome to try it.