I have often considered getting a dual shelf, since I go back and forth a lot. I decided after much experimenting that the slight variances in my tempo and form seem to allow for variances in the bow grips. All of my right hand bows except one have asymmetrical grips. It is tempting to try for an asymmetric straight grip on my coming LEFTHAND yew/pinkish I Vixen, but it is a difficult thing to explain and even more difficult to measure and then explain. Remember, for you old timers, that old black and white Marx Brothers movie where they had a gigantic single shot scene, where all kinds crap was going on at once, and then the opera singer came out and sang, "where is my shirt, I want my shirt, I'm never happy without my shirt."? Don't mind me, I shot for way too long today, ate way too much prime rib for supper and washed it down with way too much coffee.