I have been using an Herman Miller Aeron as well since about 8 years.
At the time the price was steep but I swallowed it.
Overall, people trying it for the first time seem to be amazed by the feel of the mesh, and my experience confirms that the mesh part itself is indeed truly excellent.
However, I never really got comfortable with the feel of the front edge of the chair under my legs, which I find too hard. And generally speaking, the way the frame is built make it really uncomfortable to use the chair in any other position than the standard sitting one. I wish often that I had a chair that I could cross one or both of my legs lotus-style, sit sideways or even in reverse, with the chair’s back in front, like you can with regular dining room chairs.
With time, my conclusion is that aiming for a single “best-practice” posture does not work. You need the flexibility to change your posture often, even if just for a few minutes. I am alternating between a bean bag with my laptop on its own, the aeron when at the desk with the laptop connected to external monitors/mouse/keyboard via a single-cable thunderbolt dock and the base of a low-cost office chair (I removed the back of it) to cross my legs on or simply change posture from the Aeron.
It’s exactly like programming: There Is No Silver Bullet