Plenty of people fly with the A20s. They are big, but they sound great. I felt like they were too hot for me, so they went back. Chucking them in my flight bag with charts and manuals didn't work, but with EFBs out there for most people that isn't a concern. A ton of guys also fly with the regular old David Clarks from their CFI days.
DC ProX work well for some, not for others. There is definitely a sweet spot they need to be in to be nice and quiet. I like mine. Comfortable, nice Bluetooth function as well. I also fly a 172 occasionally and they work well there as well. Not as quiet as the A20s in jets or props, but also nowhere near as much money or as hot as the A20s.
I also had the uflymike setup for a while. It was great. No complaints. Not quite as quiet as the ProX (but close), also worked fine in GA aircraft. Nice and comfortable and could be used on deadheads. Audio input for music etc sucked though, and unless you also wear earbuds they die when the battery dies and are not TSO approved. Some airlines require TSO headsets. Mine does and I only had once time in a couple thousand hours that a check airman made sure I had the TSO version, but I'm glad I did because he would have made my life difficult.
Keep in mind that not all jets are quiet. The 900 is loud, just the way the fan setup is, if you turn them off it gets quiet, but you're not going to be flying like that. 200 is much quieter until you hit 300kias, then it's still quieter but the wind noise picks up. From time on jump seats, the 175 and 145 are in between the CRJs as far as noise level goes.