The main issue I have with those Aeron things is that they're HUGE, designed for the ISO standard man and I am below the average height for a woman at 5'3". Man-size chairs are always stupidly oversized for me and don't work at all.
If you think office chairs are expensive, look at wheelchairs sometime, the good ones, the ones that actual full-time, self propelling/operating users use. Thousands of pounds and have to work for 16-18 hours a day of use and not be shit (where not-shit is a series of compromises).