The Bose X has proven to be rock solid, comfortable and works great. The Lightspeed Zulu is also well made, comfortable, has better NR, the Bluetooth works well, (although there are perhaps too many cables involved if you want to also hook up your iPod for music). The Control module design and controls do not inspire great confidence in their longevity, but so far have worked well. The Bose A20 has better NR than the X, and I would say that it is roughly on a par with the LSZulu, so I would say they are even there.
The A20 control module, however, is even more "plasticy" and fragile than the LSZulu, and indeed the Bluetooth volume adjustment knob, just fell off or broke off during normal use after about 4 flights. The Bluetooth electronics also just quit working at all, at the same point.
I called Bose and they agreed to replace the unit, but by the time the RMA arrived, they had none left to ship me, and it is now going to be weeks and perhaps over a month before they can replace the unit. First let me say that I am a good, and frequent purchaser of Bose audio products, and this is the first time I have had one fail in 10 years of Bose purchases. This experienced reliability is why I purchased their new headset instead of another LSZulu. Features and NR performance, being equal, I chose Bose. Now, I am very disappointed, and given the nature and timing of the failure, I have to say this issue should not have happened with their new $1000+ headset, and feels like a too early release of a new product, due perhaps to arrogance and greed on the part of Bose, in releasing a less than perfect new product in order to get it to market quickly. This almost immediate failure and the questionable product design, make me believe they rushed the A20 to market before it was fully tested in order to compete with the LSZulu, which offered better NR performance, desirable, up to date additional features the Bose X did not, and was clearly taking market share away from Bose in the professional market. I suspect they did not adequately test the sub components, materials and product design of their unit to make sure it was rock solid like the X is.
My conclusion is that it is potentially a good unit, and can undoubtedly be reconfigured to provide good service, but they may have to adjust some materials and 'chips' to make it right if there prove to be reliability, strength or product design issues with the product, as I suspect based on my experience. Bose is a strong company, and can, and I believe will, fix any flaws in their new design, and make it right for their trusting customers, but it is annoying and expensive to be caught in what looks to me like a "beta test" situation with a new product, and a rush to meet sales quotas instead of retaining an adequate supply of units for field failure replacements. When I spend over a thousand dollars for an aviation headset, I expect "perfect" and "well tested" and excellent Quality Control. Clearly, this did not happen this time.