okay.. g is very unlikely to kill you when you overdose, unless you mix it with other drugs (especially depressants, especially) alcohol.. it looks scary.. but it tends to be, in actuality, just a very deep sleep that the vast majority of people wake up from without problems..
meth, maybe, doesn't have as many hard and fast rules about what you can mix it with.. however, as for addiction, they are both addictive in different ways.. withdrawal from g will make you extremely anxious and pissed off, but you probably won't go rob somebody's grandmother to get more.. psychologically you'll be a wreck if you become a g addict and find your substance of choice denied you. it does wear off after 2-7 days though..
the major factor i think is that the long term effects physically of a g addiction are mild, verging on non-existant.. your body will not be devestated by the effects of the drug in the way meth can and does alter your body.. because g doesn't inhibit sleep (far from it, though it may decrease the length of sleep) or decrease appetite, you'll still be getting all the valuable nutrients and recharging time your body requires to remain healthy.. in high doses g can make you incoherent (much like alcohol), but it does not trigger psychosis the way excessive meth usage can.