Do you need to thread a lock through the helmet: chose fewer large vents.
Winter use: more helmet and less hole is warmer. Most hemets stress their cooling abilities for summer use.
Peak are good for rain.
Met helmets use a fitting system like most other safety helmts: an adjustable nylon band that conforms to any head shape.
A helmet that is moulded into the shell rather than glued is stronger.

My commuter helmet too one knock too many (after 5 years) and spontaneously cracked without ever having been in a crash.