[no skid marks]

i also feel mx helmet is the only way to go why put a less protection over your brain

Because it's not less protection, it's more correct protection. Moto helmets are designed for higher velocity impacts, and are therefor less absorbent at slower velocity ones. It's not more padding, it's harder padding.
If I hit you in the chest with a baseball bat, you'd probably better off wrapped 40 times in bubble wrap, than wearing a bullet proof vest. Sorry for the lame example.

 

[Verskis]

It's not more padding, it's harder padding.

That's not true on all occasions.
I used to have a Lazer Factory Rider DH helmet, similar to this:

It had the hardest styrofoam I have ever touched.
Now I have NoFear Optimal MX helmet, and the styrofoam is way softer, and there is more of it. I am sure the NoFear helmet is much better also in smaller crashes.

But I have tried my friend's TLD D2, and it has really soft styrofoam, even softer than my NoFear. There's just not as much of it, so when comparing these two, your claim is true.

 

[ALEXIS_DH]

whats the source to the "moto helmets have harder styrofoam than dh helmets" claim?

 

[atrokz]

whats the source to the "moto helmets have harder styrofoam than dh helmets" claim?

See sig.

On a more serious note, that topic has been through the ringer, and beaten on like a dead horse on here. Search and yee shall find.