After using my Silver Leaf Fern Chair for a month now - this chair has blown any other I've sat in out of the water! I was skeptical that the Fern's design was a gimmick, however after extensive sitting I can attest that the research and development that went into the chair's design produced the most suspended and supported backrest I've ever used.
I have sat in a range of Steelcase chairs and Herman Miller chairs, the Haworth Fern stands out amongst all of the top chairs as the lumbar support is ingenious and as a 6'1" tall 175 lb guy it fits me beautifully.
I highly recommend you test a Fern chair out, the seat is also phenomenal in that it is a high quality ergonomic seat while still providing extended comfort and you never feel like you're bottoming out. The adjustments have a wide-range and are very responsive!
It's such a comfortable chair I could easily recline back and fall asleep in it - the backrest is both a cradling feeling yet offers a dynamic range of movement within the chair where despite the backrest flexing - you ALWAYS feel supported.
Absolute work of art both aesthetically AND ergonomically/functionally.