Giro Hex?
 

Recently tried one on at REI and it fit pretty nice..
But I can't help to notice that it was advertised is a mountain bike/trail helmet.

Any disadantages/advantages?

I just bought one from REI, I really like it. I like the adjuster thing and the vents are really nice, price was OK too.

I've got one and I like it cause its got full coverage on the back of my head but still has nice ventilation. I think its great for the trails but if your riding the road I would go for something that's more roadie oriented because it'll have better ventilation (and be lighter if you care about that), which will be especially nice on those epic SS road rides.

As far as I can tell the big difference between a road and mountain bike helmet is the removable visor that mountain bike helmets tend to have.

Also, mountain bike helmets come in XTREME URBAN CAMO. I wear the cheapest road/commuter helmet for everything.

I have a Hex. It's fine and it looks a little more "xTREME URBAN" than "roadie dork" although to the untrained eye it must be hard to see a difference. I took the visor off and use a cycling cap instead.