I fly with the DC One X and have only good things to say about them. They are quite a lot cheaper than their Bose competition as well
I flight-tested the Bose and DC One X. The reason I didn't do the same with the Lightspeed Zulu is because they told me the microphone was not able to rotate through 180 degrees and was only on the left side. If I'm in the right seat I don't want the microphone on the left (I don't really care who thinks I'm a fussy so 'n' so). I really have no idea if this is true but I did ask it directly of the factory, so took it to be true and dismissed them as a result.
Between the Bose and the DC headsets I thought the Bose had a very, very slightly better ANR but certainly not anything that would be noticed in a Rotax-powered machine. I was testing them in a 200hp RV4 and a 180hp RV8, so think I was fair in my testing in relatively high noise levels. In a Cessna/Piper I wouldn't expect to notice much difference either.
What lead me to the DCs was (a)a much better build quality. The Bose just felt plasticky, whereas the DCs components are (lightweight) metal and I believe are more robust (b)I didn't like the fold-in-half headband on the Bose. I think it does a good job of preventing clamping but it's another point of failure and I felt no difference between the clamping forces of the two headsets (c)I definitely do NOT like having half a sheep atop my swede as the Bose headband. The DCs have a synthetic headband that adjusts to the temperature of your head, preventing it getting hot in the summer and cold in the winter (d)I cannot abide the way the Bose microphone bends down from the headset and then bends up towards you mouth, instead of just coming straight from the side (e)I don't want to have to break out a tool kit every time I want to move the microphone from the left side to the right side (see Lightspeed problem). With the DCs I just rotate it 180 degrees.
The Bose does have the advantage of the 3.5mm Aux input and this was one of the main reasons I looked at them. At the time I was thinking of routing my Pilot Aware audio through them but then Tim got verbal traffic on SkyDemon and I just use Bluetooth to my headset from my iPad, so problem solved.
I'm glad I made the decision I did and have no regrets. The headsets work very well indeed in my machine and I stand by all my original reasons from not going for the more expensive Bose.