I've got the Aeron and it great's for the back and looks a lot better than that Jetson's-looking Embody, but I have to use a cushion under my legs to prevent the stupid ass plastic frame from digging into the backs of my legs. I'm guessing as ugly as the Embody is, they fixed that issue so I would say go with the Embody.
Yeah I've got the right size, I think the sling starts to sag after awhile and that's what causes it. Didn't use to happen. I wish I could say I'm just getting fat, but nope - it's the chair.
FYI, Herman Miller is having their annual 15% off sale soon (like Nov 27-Dec 13) or something. Worth keeping in mind for us cheapskates. 15% off $1k+ adds up. I'm probably gonna buy an embody then, as it was super comfortable and I've heard great things about it.
if youre a cheapskate just but a refurb from ebay at 1/3 rrp cost