In terms of actual data, no I don't know how much better GHorn is over DB. I did get the GHorn in a drop last weekend and am quickly learning though :) Last night, I joined a couple randoms to take down the Nightfall. We make it to Archon, release him, and myself and one of the Randos, take position on the high Sniper perch with our GHorns. Mine isn't maxed out yet but our combined volleys dropped the Priest in under 10 seconds. We killed him so fast the first time, the game glitched and gave him back a quarter of his health and he shrugged off two more rockets before finally burning up.

Each ghorn shot does about 2.5x the damage of a truth rocket assuming all wolf pack rounds hit. I am very happy you were lucky enough to get one by the way.