I have never seen an animal have to be shipped because it had too much set to it's legs ( ie sickle hocked). I have seen far too many shipped because they did not have enough set to their legs.
I agree with olsun in regards to the differences between cow hocked and sickle hocked. Cow hocked is usually a sign of an animal with inadequate muscling. Animals that walk with their hocks almost touching usually do not have enough natural thickness and muscle development. In a well muscled animal, usually the muscles on the lower quarter,on both the inside and outside of the leg are larger and this tends to force the legs out somewhat. This allows the legs to appear to be under the corners of the body. In very heavily muscled animals, these muscles get so large that the animal appears to walk very wide.
If this cow you are considering is not excessive in the sickle hocked issue, I would not be too afraid to purchase her,provided I was willing to be very selective every year in what she is bred to. But then, I am more concerned about longevity and soundness, than just getting calves that have four posts under their four corners.