Speakers, floor standing or Bookshelfs

Unlike an HT multiple speaker system, a two channel set up with a well integrated sub(s) generally improves the overall dimensionality, imaging and tonal density of any speaker system regardless of the lower frequency response of the speaker.

@bubinga 

YES!

This is something that does not get mentioned nearly often enough.

There is a lot of ambient information in the very low frequencies, that convey a sense of space, that can be missing without the sub.

@newfzx7 

I'm of the mind, If you like the sound of your speakers why remove part of their character and then try to replace it using the sub?  Running full range you just augment the sound with the sub without taking something away first.

While I agree with you that even large floor standers will benefit from subs, there are good reasons to limit them from producing the lowest frequencies.

1. if the woofer does not have to reproduce the lowest frequencies, it will sound cleaner, lower distortion, within the pass band it is reproducing. It will be operating in a more linear area of its range. 

2. If your amplifier does not have to reproduce the lowest frequencies, it will have an easier time reproducing the rest of the spectrum. The vast majority of the power an amplifier produces goes to preproducing bass. Make the amps job easier will result in improved dynamics, and a more effortless sound.

3. I don't believe that taking away the lowest octave will change the character of the speaker. The most audible character of a speaker is in the rest of the frequency spectrum, not the lowest octave of the bass. 

All my opinion, of course.