id say noobtuboes being somewhere inbetween MW2(without dangerclose) and BO.
id also make them less noobfriendly. high priced unlock that BO did, will always explode on impact, which adds the chance of suicides, and assists in suicides with them. if i got noobtubed and saw the noobtuber killed himself, i wouldnt be pissed.
also increase the curve that noobtubes fall. would make them harder to use and thus not a problem.
all of the above keeps them usefull and removes much of the noob aspect.
I was kind of dissapointed with the GL in MW3. Course I never used it in BO (my first COD). It just seemed incongruous that a grenade at five feet could kill me but a grenade impacting on my shoes wouldn't. And as noted above it has its uses. On HC I could take someone who had just rounded a corner out, and it is great at clearing out camp spots. While I have no respect for the people who just run around with thier GL set up, lets face it, they aren't that good. Nor are they that much of a threat. Will you die from them? Of course it happens. But I'd say that i've had noob tubers miss me and die a lot more often then kill me. Its a usefull tool for when you need it.