I've lost weight recently so my Shoei Qwest Large no longer fits. I was really hoping the GT-Air would be the replacement, if only for the sun visor, but alas, the fit on the Air is way different than the Qwest-- the large is too large, and the medium is smaller/tighter than the Qwest medium. The medium GT-Air feels fine once it's on my head, but it's the first helmet I've ever tried that is literally *physically painful* to remove-- no manner of finger-finagling could get the helmet off my head without painfully bending my ears.
It's a shame because I love the GT-Air, I just wish it fit. My other choice was to go to the Shoei Neotec in medium, but at a $100 more than the GT-Air (and $300 more than the now-discounted Qwest), that's a rich price to pay just to get a sun visor (and I don't really want a modular).
Anyway, just be aware that IME the GT-Air is a significantly different fit than the Qwest.