2 seasons ago we switched to Mountain Bike Downhill Racing helmets.
SixSixOne and Gyro are the 2 main brands.
I'll never go back to a heavy MX helmet. I use to wear M2R Carbon Fiber model, and the mountain bike helmets are a full pound lighter and WAY more ventilation.
They conform to the European testing standards...and are designed for impacts more likely to be seen in mountain snowmobile riding.
DItto.
Hands down, WAY better. I will never ever buy another sled or moto specific helmet.
If you're always cold, the DH type helmets might keep you a bit cooler, but I've never in 4 years of riding them, been cold with one on, and you sweat less.
The weight of a helmet is a huge factor, so many people underestimate how much it affects you.
Nearly everyone who has tried one of ours on has switched to them & been very happy that they did. (you'll never convince me that sledding is more likely to injure your head than DH, not even close. DH is sketchy!!!!)