I did a direct comparison with the Momentum, AKG K167, Focal Spirit One and a D1001 and I found the COP pretty impressive.
I have listened to hundreds of more headphones and have a pretty clear mental image of at least 50 more headphones sound signature and technical abilities.
Of the 4 headphones The Momentum was the superior one. It has a really full, enjoyable laidback sound and still managed to have nice sparkle in the treble. Reminded me of the LCD-2 in that regard. Nicely detailed, but the details was never forced by a unnatural spike in the upper mids or treble. Nice soundstage, not the deepest but with good separation. This headphones works with pretty much all genres like a HD600/650.
Now on to the COP. This headphones do very little wrong and a lot right in my opinion. It reminded me of a M50 with better bass impact, larger soundstage, slightly less warm mids and no annoying 9k spike. According to my memory of the M50 the COP is slightly less detailed, but I can take slightly less detail in exchange for more smoothness. It has pretty good focus and speed and still managed to sound full and fun. This is a departure from the normal colder and thinner Beyer studio-like tonality and if you are looking for a analytical headphones this is not for you. This is not a headphone suited for studio monitoring as it's not that great at showing bad mixes or bad quality sound. I feel the change in tonality is a step in the right direction for Beyer however.
One of the best tings about this headphone is the adjustable bass even tho for me personally only 2 settings works good. This is good when genre hopping and makes it an easier recommendation to novices.
When it comes to genres I feel modern music do this can more justice. Electronic, pop, rock and hip hip is the forte, especially electronic music IMO. For "audiophile" music I can understand why some may prefer a K167.
I don't understand the person who said this was a boring headphone. K550, DT990, SA5000 and all Etymotics are boring headphones.
If you where disappointed by the thin and slightly spiky sound of the K550, anemic T70 or the unnatural, metallic and horribly spiky sound of almost all Ultrasone models this is a more safe buy. This is a natural sounding headphone in comparison and more natural sounding in the treble than the K167 too.
I would liked to have slightly more air and clarity, and slightly more tightness in the bass, but I understand why they went in this direction. I don't feel it lacks clarity or detail especially, but for 200$ in the year 2013, maybe it's not the final say. To me this headphone is a winner overall. This is a headphone for an average listener using a portable device or on a computer without expensive gear.
If anyone is interested in a more detailed comparison to one of the three or any other headphones I perhaps may be of service.
The Momentum may be superior sound wise, even though I do not agree having listened to a pair for a week, the comfort is nowhere to be found. Horrific narrow openings and sharp ridges on the driver makes them unbearable. The COP has humongous openings and literally a blanket over the flat driver surface.