I'd pay a bit more and get a Hex or a Xen. They look a bit better IMO (tart I know) but they also fit better and have enough protection / venting to be used for any kind of riding. I use my Xen happily on all three of my bikes. (XC / FR / DJ)
Unless you already know Giros fit you better than others you'd need to try some. I really wanted an Animas but ended up with a Met 5th Element because it fits my head so much better which, as Carlos pointed out, is the name of the game.
how about a trip to a large departmant type cycle store (DON'T try this at your independent LBS as its blatently taking the p155)
And try a few lids and shoes you like the look of find out what size you need then off to CRC just remember if an over enthusiastic memebr of staff helps you the line "they feel a bit tight" or "they feel a bit slack" how will they know ;-)