I've had nothing but DCs until I bought some really cheapies ($80 each) for the occasional 4th passenger or little kid, a year or so ago. I bought my first DC 10-40 (predecessor to the 10-30) in 1979, which is still going strong--and after it was damaged in the late 80s, DC repaired it at no charge, which sold me on their customer service. I bought my first DC 10-13.4 a couple of years later and my second 13.4 about 8 years ago.
My only complaint about the DCs was that on long flights (all day), their comfort level went down. So I modified both 13.4s with Oregon Aero comfort/hushkits, and for several years, I was totally satisfied with the DCs.
But as my hearing slowly deteriorated, I was having trouble understanding ATC, but I wasn't ready to spring for any of the 1 AMU headsets. So instead I bought a Headsets Inc. ANR modification for my original 13.4, and quite honestly, it's every bit as good as any of the Bose versions--I've flown with them, except for the latest A20 version. I have not flown with Zulus or the Sennheiser. The Zulus don't fit my ears well, and I haven't had any opportunity to try out the Sennheiser except at OSH, which isn't realistic.
With the OA comfort items and the HI ANR conversion, I have a terrific headset, comfortable in all respects for all day flying. The HI upgrade uses much better sounding ear speakers, and the ANR works very well in my noisy little airplane. The conversion is easy, if you can solder wires together or onto a circuit board. Battery life is good, around 25 hours, but they have a feature that they don't advertise--if the ANR shuts down due to a low battery, there's another half hour available by just turning it off and back on. They also offer a panel plug (not the same as the high end headsets), but I haven't bothered to have it installed.
My $.02.
Cary