Right on the mark. 100% agree (as does everyone else).
That also lends itself into the point that if you do solicit testimonials (or someone offers to write/video one for you)... ask for SPECIFICS.
The general "wow, this thing is great" and "you should be ashamed of yourself for selling it so cheap" junk doesn't mean anything.
But measurable specifics can be killer.
"Our ____ website typically sees 5000 visitors every week unless we're running a promotion. This normally brings in X sales. We decided to give your Widget a spin. I had my tech guy install it... took him 20 minutes, I'm told and we had it setup. I then let it just run it's course and today, it's been one week since the install. Our sales are a whopping 3X" blah blah.
Have them tell a story but with figures and stats thrown in.
But yes, great point about using case studies.
In fact... I just wrapped up the creation of a quick audio product (just as a bonus to my internal list, no big launch) discussing quick info creation tactics. BUT... the whole program was actually done as a live case study. Meaning, I was in fact creating ANOTHER info product and documenting the steps and progress of that in this one. So instead of just theory, it comes across as a walk-through and a case study of how I developed an info product quickly. I see A LOT of value in doing case studies.
Right on the mark!!