...no really.

I'm buying a cycle helmet online. I want one of those ones that are more like BMX helmets or something, the ones that look a bit like WW2 GI hats I guess. Like this:

http://www.wiggle.co.uk/bell-faction-helmet-2011/

or this:

http://www.cyclesurgery.com/pws/UpdateBasket.ice

The only reason I want one like this is cos it looks more cool. What are the drawbacks? Less safe for road biking? Bad ventilation? Doesn't actually look cool? Tell me.