Ok, I checked these out today at lunch. I was actually going to look at the Icon Mainframe Halo, but the lousy dealer here had only the Alliance. I tried that it didn't fit well at all.
The first helmet I tried on was a Scorpion EXO-700 in XL. First off, the appearance of the helmet is more of a $400+ helmet, nicely done. When I picked it up I noticed the materials and craftsmanship were much better than I expected out of a helmet in this price range.
The fit was excellent, the thing I liked most were the cutouts for the ears. My Shoei RF-800 leaves my ears pushed against my head and after a few hours it's downright painful. Not a chance of that happening in this helmet.
The attempts to allow it to breathe were evident. There are holes all over this thing. The liner is removable, though the snaps looked like something you wouldn't want to use too much, they might wear out.
I checked this company out online and all of their helmets are made in the USA; simply astounding considering the price and my initial reaction to the quality.
For folks that sweat a lot, the "wicking" fabric (I'm guessing polyether) is a nice feature.
I have not road tested it, but I'm tempted to just take the plunge and get it.