The A20 is the way to go, assuming you're happy with it now.
I have and use the older Bose X on every airline flight I fly. It is very good. I've worn the A20. It is better. I will buy an A20 as my next headset.
I flew the 737 for 2.5 years. I enjoyed it... and the fact it had an intercom system. I recommend you use it. Along with your A20, it will save your hearing.
I now fly the 757/767. 99% of the pilots say it is God's gift to the airline pilot. I'm in the 1%. Two of the many detractors for me are the lack of intercom and the very noisy cockpit. I use my Bose all of the time. I find that there are noise levels where having the headset on with the ANR active is actually better than using the cockpit speaker with the headset off.
Not all agree with me, but that's fine. I'm an odd duck. But a good ANR headset will reduce fatigue on a 5-6 hour transcon / trans-Pac.
Bottom line: your A20 is perfect for airline use.
Edit: unlike the military, the airlines will not give you any "disability" or "compensation" for hearing loss. So don't lose what you show up with.