I'm currently using a Bell Faction skate-style helmet. However, now that it's warming up, I'm in the lookout for a lightweight road helmet so when I take my helmet off, it doesn't look like I've slathered petroleum jelly all over my hair. My commute is 40km round trip.

Depends where you're riding... If I were commuting through a downtown area, I would probably stick with a skate-style helmet for protection for all types of falls and collisions for those just-in-case moments. But if I'm on long stretches of road, then an aero-helmet all the way.