The Airobic is a little stiffer in the tip and tail than the FK, but it is strange to even say stiffer when talking about the Airobic, because as kilinger mentioned, it is still a very flexy model. The Airobic gives you just the right amount of resistance for presses. If that is your primary interest, you will dig it.
Well, I don't know how to take this now. (this is also adressed to snowklinger) My Fun.Kink, which technically is softer than the airobic, had practically no chatter, but felt extremely stable and locked in on crazy eurocarves, even though it felt pretty soft. From my experience with it, although bataleon gave it a 3.5/10 flex rating, it felt considerably stiffer than expected, probably more like 4.5. It was quite easy and ridiculously fun to press, but felt like it was giving me just a little more resistance than need be. Could the airobic really somehow be so unstable in comparison, if it's less soft and has the exact same contact length, 116cm? Also, i have fairly stiff bindings (forum republic 08's), so i'm slightly covered in terms of stability.
if it matters, i'm not particularly heavy, 68kg/150lb, and at the moment i'm not hitting anything bigger than mid-large-ish kickers, nothing huge. Also, yes i do absolutely love presses, hence how intensely i'm considering stiffness.
again, could someone clarify if my understanding is wrong, that same model boards are softer when you go down a size? I thought Snowboard companies do that to justify their flex-ratings, since a smaller size obviously is for lighter people, that will find the same flex harder to press. am i wrong?
PS: I realize that flex-ratings are far from accurate