As far as I'm concerned, all lids which have passed the 'Gold' standard will offer the same protection. All you get for the extra money is better quality fit and finish, with a possible after-sales service.

My heads fits a Shoei shape, I don't seem to fit Arai's as well. My OGK protected my bonse when I bounced off the tyre wall and and I've not suffered any long term illness. (shut it Monkey!) Most club racers wear HJC or whatever is cheapest as the KNOW they'll bin it sooner or later, and the extra money doesn't buy extra protection.

All IMHO of course!
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball