a little update
I bought the one in post #2. The battery lasted 9+ hours. I tend to wear a small or med bike helmet. The only helmet they had for sale was med/large. I thought it would work. Felt fine in the store.
Felt fine for 30 min bike ride. I noticed on longer bike rides my head would start to hurt. I guess that from making it go all the way tight so it does not sit too low. anways I returned it. if it fits your head it looked great and can been seen from a far distance.