Agreed. However, I think testimonials done the right way has as much impact as a case study. For instance, a testimony by a recognized & credible person in that niche would instantly boost the perceived value of the product (imagine if Jeff Walker gives his testimony on your 'how to conduct a product launch' e-book). And if the testimony contains specifics rather than generalities ("Great product...learned a lot from it..."), then it becomes just like a case study.

The advantage of testimonies is that they are personal and real hence people can identify with them. So the bottom line is that both case studies and testimonials are good for social proof.


Just my 2 cents worth

Clarence