Air attack vs air attack shield? Giro helmets

I am looking at getting the air attack also, but i am going with the shieldless version. I keep my sunglasses on durring the run.

also, the shield seems like it would alow for less venting.

If aero is your #1 concern, you should be looking at other helmets.

The Air Attack is right between the Aeon and Selector. Much more aero than the Aeon, much more ventilation than the Selector. One of the Giro guys who worked on the AA said that there is essentially no difference in drag between the shield and a regular pair of glasses. He mentioned the only problem is when the rider doesn't go with either option. 

Has anyone actually received theirs that ordered the shield? I heard giro is having some legal issues with kask that might prevent it from being sent out

I don't know if I'd say "much more".  12% is what's been quoted (12% better than the Aeon, 12% worse than the Selector).

I'm not saying it's a terrible helmet.  There are other reasons you might want one - better performance at non-zero yaw, or you want something you can also use as a road helmet, or maybe you just want something that'll fit in your carry on luggage

But the OP wanted aero and that leads to the Selector, Air Advantage 2, Specialized TT2, etc.

Yeah I agree it's definitely not the most aero helmet out there. I guess numbers are relative. I look at the 12% as being much more, but I also consider it much less than the Selector. I'm looking at getting it because I've had some neck issues which make it pretty hard to stay in the perfect aero position for 56 or 112 miles. I like to keep my head down for certain periods and the "12% less aero than the Selector" will result in a much less drastic time loss than having the Selector's tail pointing up for a while! 

Also, the OP never said he wanted the most aero helmet, he was just concerned that however aero the AA is, it might be less aero without the shield. 

Mine is supposed to ship in a week.  I contacted the seller (Ebay) and he's already shipping them to those who ordered in February. So I don't think there's anything to the Kask legal issue.

It was bryancd's IMSG race report from 2012 where he KQ'd.  Then he got reports that the visor is actually not as aero (for some) and he didn't use it for Kona.  Whether or not it was more or less aero for him is really unknown.

The thing about aero helmets is that it is HIGHLY individual.  In general, an aero helmet will be much better than a standard road helmet, but it's almost impossible to say for sure which aero helmet is better (or whether or not a visor is better) unless you actually test the helmet for yourself in a wind tunnel.  Granted, there are some tell tell signs that one aero helmet might work better for an individual based on how it fits on the riders head and how the tail matches the curvature of the riders back...but it's not as easy as many people think.

Just look at the progression of aero wheels.  Just by looking at them, you would think that V shape rims would be much faster than the more common U shaped rims you see now...but that's clearly not the case when you actually test them in the wind tunnel.  So try not to jump to too many conclusions when it comes to aerodynamics.