I don't think the standard pinch grip is especially useful when using smaller knives. Typically, you pinch at the balance point of the blade to give you better control of the tip of the knife, but since the blade of short chef's knives are so much shorter and lighter, the balance point is usually much farther back -- typically at the bolster or even in the handle. So I often end up holding the bolster on my shorter knives. It's still a pinch grip, but it's non-standard because I'm pinching the handle/bolster/ferrule and not the blade itself.
You can also modify your pinch grip to get your fingers up and out of the way to provide board clearance for your knuckles. I use a similar grip to the one featured in this video when using my shorter petties (even my paring knives) and have plenty of clearance.
You can also adjust your cutting technique to use with shorter blades. Up and down chopping isn't really the strong suit of petties -- at least on taller product. They're better suited toward draw/pull cuts where you leave the tip of the knife on the board and slice backward through the product. But if choppy choppy is your thing, they also make tall petties.
