frequency response - B&W vs. Monitor Audio

Bob says...Those are only numbers, its how they sound that counts. Besides there is very little music below 50hz.

I agree with the first sentence.The pitch of the sound is what makes or breaks it.
I disagree with the second sentence to a certain extent.While there may not be a lot of music below 50Hz,what's there is important.The lowest registers of the piano and organ,pipe organs,tubas,etc. fall in this range.Again,the pitch of the sound is very important.Of course these are just my opinions and everyone is entitled to their own.

Also, regarding the high end frequencies, very few folks can hear even up to 20kHz, as far as I know.

Don't forget the room and setup!
Also, when it comes to LF extension of above named, I see no tolerance and certainly no ref to quality of sound.

Two points: everyone is right, frequency response, in and of itself tells little about the "sound" of the speaker. Second, response above and below what we can "hear" influences out perception of the sound that is audible to us. I find that my subs make music sound more realistic even when there is supposedly no content present in the range they cover. The human perception system is fascinatingly complex and not yet completely understood. There was a recent experiment in which it appears that our sensitivity to ultra high frequency sound was not through our ears but through the body in some way. This sounds weird and it is but when the body was blocked from the sound and the ears left exposed the sound could not be perceived; when the ears were blocked and the body left exposed it could. As Haldane said'"The world is not stranger than we imagine, it is stranger than we can imagine".

The lowest note on a standard piano is A1 @27.5hz, and if you double that to 55hz that is the next A up (A2), you IMHO
are missing a lot of musical sounds from below 50hz ie some low notes on a bass guitar,synths,organs etc and that last octave again IMHO is vitally important for depth, unless of course you only listen to the Triangle, Flute or solo Violin music.