Mike Palmer once told me that the best grip for bow would be something that was close to a broom handle. He said that it would reduce torque, and provide a natural hand position.
It made sense to me then, and even more now. Each of us have a perfered, based most often, and wisely so, on comfort.
Having said that, we can't take the bowyer out of the equation. They developed the design of the bow, which is different from others often times, but the same in one important way. The pivot point is the only spot on the handle, for those that have a visible one, where pressure is to be placed. I believe that failure on the shooters part to understand and conform to this design feature results in more frustation in tuning and shooting.
Even with a really low wrist grip, the pressure can still be placed on the pivot point, which even when the heel of the hand is down, can be applied to that part of the grip.
When done in unison with the design, tiller, the bow shoots to maximum efficency, providing great launch, and accuracy.
Now some perfer the low grip, and some like the palm filled with a meaty grip, either way, in most cases a firm but light grip that allows for the web of the hand to work with the pivot point will allow the shooter and the bow to become one. Of course we know what happens when that occurs, we shoot, we hit, and we do it with great regularity.
I love it when a plan comes together...