It will not serve its purpose, in case any of these sections are not up to the snuff. The best thing about sales letter is that you can try different headings, styles, and body texts (since it doesn t cost you anything to try different styles, formats or layouts), in the end you can continue with the one that brings the best results.
When writing a sales letter for a wholesale, retail, distributors, or any other kind of trade businesses, remember that it must be having some figures to back up your claims and testimonials from other businesses. You can also draw attention to the profit margins, since most of these businesses (e.g. wholesalers, retailers, and distributors) will be buying with the sole purpose of reselling for profits.