Now this is some interesting stuff. Are you suggesting berzerk with something like twice upped bonesnap, will be more effective than waiting n letting merc kill, i.e. with 2 x 6 lem'd crystal swords? And then switch n hork with the swords instead? It may do more damage. Twice uppde bonesnap deals some pretty cool damage, i've used it twice in a barb season, even just with concentrate is good EVEN in hell mode!! But i can imagene with zerk, will do crazy damage. But no leech though. But as we all know, footsies, like a boxer, sneak in, swing the hammer, sneak out, is the best option here. Step - BANG - step.
Some interesting stuff there.
Well you can make Grief in a two handed Sword and the Berserk skill multiplies the Added Damage significantly, and for Leeching, you can also use the 1 base Concentration skill that the Barbarian will have since it is on the same path as Berserk skill right? Also, the 1 Base Concentration skill can be used vs Immune Magical monsters as well, like when you are in the Throne room. Of Course when killing off the Seal bosses in Act 4 would be a breeze, Howl off the lesser minions, kill the seal boss with Berserk, horck the remains and pop Diablo fast and kill him off ... of course you can not horck his remains. As for council it is just tele in, Howl, kill, tele in howl kill and then horck because they are dead... go to Act5 tele to pindle howl Kill Pindle and horck, walk/run out, howl the lesser if you haven't go to Shenk wp, tele north, howl, kill unique, hork remains, tele down to Shenk, howl, kill Shenk and hork any remains that are there.
You can use Bonesnap if you want, just use Conc for leech.
It is just a matter of how you navigate your run to how fast it is, using the merc as kill speed for a GF barb is past by due date... the original Leap was built when Synergies, Respec and 1.10 runewords never existed, it was great, also the old Frenzy GF barb was created then and of course the Original Berserk barb build by Bigsipo ... with Respec, 1.10 runewords and synergies, the Barb is way more versatile as support, tank and killing, has the same FCR bps as sorc, great IAS bps, and Berserk dealing magical damage equivalent to a hammerdin, however, no AOE ability in killing.
Sorry, off on a tangent, I love the Barb because of versatility in build with better chances of MF & GF with Find Item skill.
Take a look at the Barb skills and synergies ... Berserk & Battle Orders and synergies, they basically compliment each other, and of course 1 base Concentration gains from Berserk...

But you know all of this.