I've got some rocky ground also and it is hard on equipment. How well a disk holds up to it, is mainly dependent on the make of the disk. A heavy well made disk will do surprising well on rocky ground. Some models are equipped with "rock flex" hangers but adds significant expense. Using a chisel plow or similar equipment prior to disking is one way to alleviate some stress on the disk, but isn't absolutely necessary, with a well made disk. I've had a Athens model 127 for eleven years now and it does an excellent job preparing a field. So far I haven't had any issues with it, rarely do I use a plow of any sort any more.