Wow, this sounds so amazing. I have never spent any money on a desk chair and I have the worst neck pain + sciatic pain + shoulder pain every day now. This chair seems heavenly.
I have an Embody. They are fantastic chairs. Couple of quick things you should know:
* They're heavy as hell. Probably the Aeron is too, but I was shocked just how heavy the chair was when I was bringing it up stairs.
* They aren't very adjustable--kind of. The whole thing about the Embody is that it, in theory, adjusts to you by itself. The tradeoff is you have quite a few less axes of manual adjustment than you do on most ergo chairs. In particular, there's no lumbar support setting--instead it has a back curvature knob, but I've heard from people who couldn't find a good fit. Test it before buying.
* They don't use cushions.
I can't remember if the Aeron is like this too, but the Embody seat uses [several layers of] plastic webbing as a spring layer and then a lightly padded fabric sling on top that rolls under in the front (it's extendable by essentially unrolling it). The back is the articulated skeleton and a frame with lightly padded fabric over it.
It is quite comfortable, but you will notice the webbing causing the fabric to wear a little in its pattern after a few months, particularly in the seat. You don't feel it at all, though. Just keep in mind it's very much a firm support ergo chair, not a comfy exec chair.
That said, I love being able to swing my arms backwards to stretch my shoulders and chest and absolutely adore being able to lean back and arch my back to stretch with the chair following my back curve and arching with me. It even twists with you some.
When you do get it dialed in right, it's like sitting on a super-articulated back brace with a butt hammock and wheels.
Edit: also, be careful how you buy them. If you expect the Herman Miller warranty, make sure you get it somewhere authorized. Most of the really cheap offers aren't. Your employer might help. I went through my then-employer's furniture distributor as part of a larger shipment, so I got it for about 50% retail.
My neck and shoulder pain went away after I started kayaking. I am not saying it is for everyone, and I cannot say for sure even that it worked for me, but I suspect it did.
I started doing push-ups every day. I hate push-ups and I am not very good at them, to make it easier I do them on an incline and it has helped tremendously with my shoulder and neck pain.
