First class help by Jordan, suggested the Ergoback Air for me and it fits me perfectly. Much appreciated!
Jordan recommended the ErgoBack Air based on my back symptoms and so far so good, really comfortable.
I got the Ergo Back with the small seat pan. Very happy with all the adjustability that it offers.
I got the small seat pan option and it fits me perfectly. I've struggled for ages to find a chair that fits properly, so I'm very happy :)