It's all in my RIGHT hand, in the case of my Kimber. Not the fore-end/left hand. If my trigger control is good and hand pressure is consistent I shoot small groups. If not I pull flyers to the right.
I don't know the "truth" of whether or not it's better to control the fore-end for everyone. I do know that for myself, I'm best off minimizing my points of contact with the rifle. Grabbing that fore-end adds a whole other point of potential mayhem from ME. Where I've found consistency is in preloading the bipod forward and in right hand position and trigger press and follow-through.
