I teach at the elementary level. I’ve pilot tested several textbooks in several curriculums. After using many publishers’ products, I’ve got a feel for what works well for me, and what materials I need. But what’s most important is how well the students work with the materials. If the students struggle with a pilot curriculum due to poor presentation, then that curriculum isn’t going to get my vote. And if there are mistakes in the materials, the sales rep is going to get an earful from me, but not my business (I hope).