I think you like them because the group as a whole doesn't seem to me to behave the same way or have the same feel during lives, as most rock idols.
That certainly is true. I hate rock antics and either on stage as at tokutenkai they behaved very idol-like.
Anyway, they have their second One Man today. It celebration of it some performance from Decembre:
I also found a good recording of some Tsubasa Fly.
I know they have their own thread but I think some of you will be curious to know how Bellring Girls Heart has started, before they put on their crow uniforms