PSB Synchrony One

Response curve is an average of five measurements:
on-axis, 15 degrees left and right off-axis,15 degrees up and down off-axis

0 / 15 / 30 degree off-axis responses

THD+N @ 90dB (50Hz - 10kHz)

With regard to objective evaluations, PSB Synchrony One is one of the best measured audiophile loudspeakers. I love their nearly-constant direcitivy, truly full range response with great linearity, Needless to say, their price of $4500/pr is extremely competitive comparing with other competitors in the same league (look at the price tags for Wilson Audio Sasha W/P or Revel Ultima Salon 2).

Source: http://www.soundstagenetwork.com/measurements/speakers/psb_synchrony_one/

Yamaha NS-1000

Measurements should be interpreted very carefully because it's not a free-field response but a in-room response, although the room where NS-1000 was measured behaves very well.

You can also find an alternative crossover design that is claimed to do better than the original one of NS-1000 in terms of harshness in mid/treble.

Source: http://www.troelsgravesen.dk/Yamaha-NS1000.htm

Bowers and Wilkins (B&W) 800 Diamond

Free-field response (Semi-anechoic)

Acoustic Contribution

Horizontal Directivity

Vertical Directivity

This set of measurements doesn't look bad. But small linear distortion in midrange is appeared. Directivity pattern is not very generous for the price range.

Source: http://www.stereophile.com/content/bampw-800-diamond-loudspeaker-measurements

Bowers and Wilkins (B&W) 802 Diamond

Free field response of 802 Diamond (Purple trace)

On-axis response is clearly less linear than previous B&W models. Some argue that new midrange units of Kevlar cone might result in such linear distortions.

Source: http://www.hometheater.com/content/bampw-802-diamond-speaker-system-ht-labs-measures

Bowers and Wilkins (B&W) Nautilus 802

Upper: Free field response (black), listening window average (green), first reflection response (red), and sound power response (blue)
Lower: Diectivity Index at first reflection (red) and sound power (blue)

Generally flat response at on-axis is shown, but DI pattern looks a bit problematic at high treble range. Also like the comment in the graph, sound power problem is appeared.

Source: http://seanolive.blogspot.com/2009/11/subjective-and-objective-evaluation-of.html