A molboard plow is good for turning under crop residue, cutting off deep perenial roots, and breaking up sod type ground.
A chisel plow is good for going a little deeper, breaking up hard-pan (if not too deep) or tight clay soils, stirring in fertilizer, and keeping some cover on the soil for those soils that want to wash or blow away.
Each has a purpose, depending what you are trying to accomplish.
The springs & the springy steel of the shank itself should handle rocks better than a molboard plow if it's designed right.
The 'new' technology of farm tillage is slot tillage. These are very thin shanks that go deeper than a chisel plow, and shatter very lightly through the hardpan, but leave the top nearly unmolested. This is to eliminate erosion from wind & water, and allow most of the ground to be a hard traffic-bearing soil structure from year to year, with thin fractures in it to allow roots, rain, & nutrients to get in deeper. I'm not sure how these thin designs will handle rocks, as they are designed to cut the soil, rather than shatter it like a chisel plow.
--->Paul