I picked one up a couple of days ago, I was chatting with someone else who rides and he was raving about the Airhawk as well. Haven't had a chance to do much more than a 30 minute ride on it and while so far it does feel comfy I won't be able to tell until I go for a 2+ hour ride.
Grn14, one thing I did notice is the air moves when you are accelerating hard. The first time for me it felt like I was about to pop a wheelie but leaning forward and knowing what will happens made it a non-issue really quickly. Probably shifts a bit if you're braking or cornering aggressively as well but there's so much gravel on the roads here I'm not going to be testing that aspect for a while.