6 points actually.
And actually, doing the numbers, if 30 Ork Boyz hit a 10-strong Grey Hunter unit of roughly equivalent points - i.e. mark of the wulfen and a power sword - then with Counter Attack, the Grey Hunters would put out around thirty to thirty five attacks (Mark of the Wulfen), of which half would hit - so we will say 16 - and a further half would wound, leading to around seven or eight dead Orks. That would leave twenty three or so Slugga Boyz fighting back ninety-two attacks, half would hit - so forty-six - and half would wound - twenty three - which assuming average saving rolls would see about eight Grey Hunters die.
Even with shooting thrown in (which opens up things like cover saves, line of sight, etc) it is definitely no guarantee the Grey Hunters would come out on top. Plus you would then have to account for the Ork shooting...