In the early days of the North American EIFS industry, the subject of "impact" was a hot topic. Basically, the issues centered on EIFS' resistance to getting beat up or lack thereof. Many competing building wall industries were looking for an angle to stem the onslaught of EIFS, and fueled the fire about this supposed weakness of EIFS.
Over the years, many ways have been developed to improve the impact resistance of EIFS. A related issue was the whole matter of "how to test how much impact resistance a given EIFS has."