I don't see a point in powerful roar I rarely saw DWs use it unless in ranked and seeing the GN is timed there is no point wasting sp on it when you can kill more mobs in your normal form.
This is my build and i'm just gonna stick to it: http://dborevelations.com/forums/index.php?action=skillcalc_class5#Dark-Warrior-050050014001000010400000333000015510101401351053030
Not max Powerful road I hope the healer will be very strong in your party.
I played with a friend dark warrior I even use the healer constantly takes aggro with heal if you do not Powerful Road in pve.
And it also protects other members as a turtle for example, which easily takes aggro.
Powerful Roar max in pvp is not necessary.
If the Healer dies GN may be an option that can help to finish a boss in pve.
And if he does not attack, he can lose his team.
One is enough, but it can play a big role in pve.