[euccastro]

I own an Aeron, and I used to have a Mirra at work. If I had my money back, I'd go for the Mirra instead. It's still in the luxury price range, but a bit cheaper, and to me it felt better. I used to spend more time sitting in the 'proper' position in the Mirra, while in the Aeron I'll often slouch, cross legs, and otherwise change posture. Maybe I never managed to adjust the Aeron just right. Mirra is less configurable, but it just worked for me, so I count that as a plus.

Even cheaper chairs are a significant investment, so I suggest just try sitting on as many as you can, and don't buy one that you couldn't try.