As has already been said, there are arguments for both expensive and inexpensive helmets.
It's similar to the thread elsewhere on tyres. Are Michelin's really that much better than Toyo's, for example? My philiosophy has always been to go for the best I can afford that gives good value for money.
My Shoei is 8 years old and still going strong. The lining is fine and I don't have any problems in scrutineering.