I use the Petzl Elios helmet for all the climbing I do, I use it cragging, winter climbing and alpine climbing. As its only 305g I actually hardly notice it is on my head, it is really easy and quick to adjust as it just has one adjustment dial at the back. This means putting a hat on underneath the helmet is no hassle what-so-ever. What I love most about the Petzl Elios is that it is super tough, it can take a lot of abuse.
I’m onto my second Elios; the first Elios I had broke after 5 years heavy use i.e. wearing it 4 times a week, multiple rocks hitting it etc. eventually it actually just cracked slightly at the front, when I was sitting on my rucksack with the Elios inside. After breaking it I decided to test it to destruction so hit it as hard as I could repeatedly with a hammer; the end result was that I could not make the crack bigger, and this didn’t damage the helmet in any noticeable way. So the conclusion of this unscientific test was both 1. I’m not very strong and more importantly 2. the Elios is incredible strong. When I hear the whine of a falling a rock and I’m trying to hide my entire body under my helmet I have the reassurance that the helmet is super strong even if I don’t fit beneath the whole helmet!
One down side of the Elios compared to a Meteor III is that the Elios does not have as good side impact protection. Side impact protection comes into play when the helmet is protecting your head in a fall rather than things falling on you; as you are more likely to hit the side of your head. The Elios has expanded polystyrene on the top, but not in the side, whereas the Meteor III is made entirely from it, so gives much better side impact protection. If you are buying a helmet only for cragging then the cycle helmet type ones i.e. Petzl Meteor III and Black Diamond Tracer are the best option. The disadvantage of the Meteor and Tracer is that they cannot take repeated blows i.e. if they are hit my a reasonable size rock then you will need to retire them, whereas a hard shell helmet like the Elios or Ecrin Roc can take repeated hits (though it is advisable to inspect any helmet after anything hits it and retire it if you suspect any damage).
The Elios is ideal for someone who participates in a range of climbing activities, being lightweight, able to handle abuse and a variety of knocks while still giving pretty good impact protection if you fall off.