I hit the ground at 30km/h last season, didn't really think I hit my head hard as my helmet cam took the initial impact which didn't look too bad either (I'm still using it with a few scratches). I ended up deciding it wasn't worth the risk, took apart the helmet and discovered a crack in the foam. It was a 4 month old (or so) $350 helmet
.... Its not like I'm rolling in $$$ either - I'm a student with no job at the moment.
If its not good enough for you to use, why would it be good for your passenger? (unless you don't care for their life).
Heres the pics of my helmet:
http://www.gtamotorcycle.com/vbforu...d-after-fall&p=1952456&viewfull=1#post1952456
The crash:
http://www.youtube.com/watch?v=fSyuVb_YuTA