I love this chair. I actually went and bought a second one- one for work and one for home.I'm a big, neckbearded programmer, and true story, I have a fake hip, so finding a comfy chair I could sit my buns of steel (actually, my ortho told me my buns are some sort of ceramic-titanium alloy) in for 8+ hours was a challenge. I've tried a few chairs, but DX Racers are just awesome.First of all, they just look cool. They really do. That cute girl in accounting will HAVE to give you her number if you roll up to her in this bad boy and introduce yourself within the boundaries of the Sexual Harassment act of 1978. Swag.But it's not just all looks and no substance. Its construction is the best of any chair I've sat in. The base is metal instead of the usual plastic, the coasters glide beautifully across even carpet, the padding is comfortable yet supportive, and it even reclines like a car seat. It's full-back, and the back comes way up for the average person, so leaning back doesn't snap your neck. The seat and armrests are also a bit wide to give your tukkas some room. Overall, it's built really well and someone engineered it with a lot of thought behind it.I'm trying to find something, anything, bad to say about it, but I can't think of one. The price, maybe, but if you spend most of your day in front of a computer, it's money well spent.As far as the difference between all the models, I'm not quite sure. The second chair I bought was the FH08, but other than the style and the armrests being able to swivel, they're pretty much the same.