Perfect fit, nice shoes
I've been wearing these for about 4 months now, and put on quite a few miles on both road and dirt. I decided, rather than buy a mediocre pair of both road and mountain shoes, that I'd just get a nice pair of mountain shoes and use them for road, since the difference anymore is primarily the tread and bolt pattern. I get a few funny looks on the road bike, but the shoes are well worth it.
The carbon sole-perfectly stiff, but still walkable. If you're familiar with Sidi shoes, you'll know that while the bulk of the soles are incredibly stiff, the toe area, particularly in their mountain shoes, flexes nicely to allow you to walk/hike if necessary. Gir emulated this, and did it very well.
The tread - Passable, but not ideal. Shimano typically uses a soft durometer rubber on their mountain soles, and Sidi uses a harder plastic on their Dominator 5 shoes, and a softer compound on their replaceable SRS soles. The soles of the Gauge resemble the Dominator 5s pretty closely, but a bit firmer. This makes walking and hiking in them tough until you start to shred the plastic and it gets grippier. About that shredding. It's probably the only real knock I have on these shoes, and the bulk of the reason they get 4 out of 5 stars. The tread and soles look absolutely beat after half a season. I've hiked on some rocky terrain with them, but the wear seems faster than I would like. A replaceable sole would be an awesome option, and would definitely take these into 5 star land. The toe spike compatibility is a big plus in the early season when the snow's still melting.
Fit - Perfect. Game, set, match. Giro found the perfect blend of European and American shoe fits. For reference, I wear a 48 in this shoe. I find a Sidi 49 Mega much too large, a 48 Mega a touch too wide, and a touch too short, and Sidi's standard sizes too narrow. I wear a Shimano 49 fairly comfortably, but it's a bit long. I like that these shoes are not a 'wide' but a 'high-volume.' For my feet, this is perfect. I initially thought they were going to be too short, but they stretched just a bit, and now fit so perfectly that I'll buy another pair regardless of my issue with the sole, when I finally wear these out.
The Supernatural Fit Kit comes standard with these shoes. It's pretty slick. Giro includes three different arch support pieces; low, regular, and high arch support. They attach with Velcro to the footbed so you don't have anything moving around or causing problems. I started with the low because it most closely matched the stock insoles in my Shimano shoes, which I was wearing just prior to picking these up. I then stepped up to the medium after a week or so, and finally to the high, which gives a really nice amount of support without adding bulk to y already bulky feet. They're comfortable for hours on end, in both road and mountain style riding (long, steady grinds, and punchier, quicker, higher-intensity efforts).
I definitely recommend these shoes to anyone who has found themselves just between a regular and a wide shoe, or at the upper end of a given size.