I used to do this many years ago because at the time, I found road bike helmets were often lighter and more sleek than similarly-priced MTB lids. Anyone else prefer to buy a road helmet and use it for MTB, or for both?
I’ve also tried wearing an MTB helmet on the road, but I found the visor blocked my vision too much based on my position on the bike.
I have used a Giro Atmos for all my rides ( road, cyclocross, and mountain ) for years and have liked it but I just ( like 2 days ago ) picked up the Troy Lee Designs A2 because after trying it on in the shop found it to be very comfortable. Will follow up if I decide to switch back for my mountain stuff.
Years ago I used road helmets when I was more XC race oriented. Then I had an eight year break from MTB riding, and, when I resumed offroad riding 4 years ago, I started using MTB helmets with visors. The visor comes in handy at times to block the sun and sometimes will deflect small tree branches as well.
This year I switched to a Bell Super 2 helmet, which offers even more coverage