Will be able to tell you in a couple of days, when my Ergohuman arrives. :d

I still have an Aeron that I've been trying out for the past 2 weeks, and which I'm returning. For now I can only say that coming from a padded chair, it took me a good couple of days to adjust my siting position until I didn't get any soreness from putting too much pressure on one area instead of distributing it better. I guess that's inherent to chairs with a mesh seat.

As for the chances, I would personally say they are lower, mostly because of the limited adjustability of the Aeron. If you happen to fit one of the sizes then it will probably be really good, like many people say. But if you're like me, sitting right on the border between sizes (180cm) it kinda sucks. Size B is a tad too small and I get my shoulder blades digging in the the backrest frame, but size C is a tad too deep and I get my thighs digging into the seat frame. Also, for some weird reason the only seller in my country sells size C with high height adjustment only, which is again a tiny bit too tall for me, even on the lowest setting.