Smith maze will have a thinner fit but the most padding and is rounder so it will fit the beanie good. Don't like the giro shiv not enough padding, very hard an it makes you feel like yo have a concussion on any fall to your head. Dont kno much about the receptor bug but definitely the smith maze is very good for what your wanting.
I tried on the Maze and noticed it fits really high on your head. So to keep it on tight you would have to tighten the chin strap a ton. I went to my shop and tried on the receptor bug and loved it. Fits really well and won't fall of. Its also pretty comfy. Just my 2 cents