Lash does something entirely different and is not a good comparison. Jaws is NOT that big of a deal. Yes, it is potent, but it isn't the end all. If they are putting the 400+ points into HQs to get as many Jaws as they can, then they are going to be hurting in other more vital areas, like Troops.
Their Troops cost around 150 for a full 10 man squad that is armed like CSM squads. I don't see a problem here. Plus they get free 2nd special weapon in the right conditions... The two psychic powers are comparible in that they both affect a whole squad. Perhaps more... JotWW is more devastating in that it just remove whole models without any interaction from your opponent. You roll, they get swallowed... At least, with Lash, one can roll some leadership...
Long Fangs have always had that ability, so it shouldn't be a shocker to anyone nor warrant any complaints. It is fair, since they cannot have ablative guys to soak up wounds like a basic Dev Squad can.
The problem is not the Long Fangs. The problem isn't even that power. The problem is allowing people to have upto 4 of them running around. And it isn't even an implicit rule that allows it... It is allowed because people choose to interpret the limitation as bypassed when you have different combination of psychic powers.
I say you cannot have any of the same psychic powers among them. My hope is that an FAQ would restore faith that the Space Wolves are not the greatest Psychic Force in the Universe. Speaking of which, how come Tzeentch Sorcerers have weaker powers than those drooling puppies...
4 rune priests 400
4 troops of Grey Hunters, no specials 600
3 Heavy - Long Fangs 500ish
enough to ruin anyone's day...