Positive feedback is good for any business. For those who've never bought anything from you, should they learn that other people are satisfied and can vouch for the quality of the products/services you sell, it would be easier to convince them to buy something from your site. Soliciting testimonials [from your clients/customers] could get you such "endorsements." However since scammers have abused this [using (fake) testimonials to deceive people] having fancy testimonials on your site could be counter-productive. Should you take the risk and hope for the best?