Helmet locks, normal ones too

Hello all, this is going to sound pretty silly I am sure, but I have never used a helmet lock like the one on the VFR and like a true doofus, didnt read the manual on its operation. Can someone point me to an online manual or how to use those little hooks? Are they really safe for my $500 RF-1000?
I am getting a disc lock today so that I can leave the bike without being QUITE as frantic about checking on it, but I want to know if the helmet lock is worth anything.hwell:
Also, do most of you use disc locks, or is a U-lock the way to go? Or should I just hire a personal bike watcher?