helmets: road vs off-road

It's not like I know a whole lot about helmets, but the only real difference I see is that MTB helmets have the little visor. I've used one of those for all my tris and if it ever gets to be a performance limiter, well ... look for me on the Olympic podium. What difference could it possibly make??

I have an MTB helmet that used to have a little visor until I recently removed it. I just bought my first road bike and because of my position on the bike, the little visor blocks my view of the road. Taking the visor off now lets me see where I'm going.

Mike

I have 2 MTB helmets, and one of them I use for road and tris as well (the other is a full face MTB helmet ). I've tried riding on the road without the little visor, and can't. I've found that it blocks a lot of the sun and keeps the glare down while riding in sunny AZ, which allows me to see better. And I've gotten used to it. I've had no problems with the visor at higher speeds, so I just leave it on.