Hi,
SPIN Selling's been around longer than most people think.
I read the book, and took a training class as part of a corporate learning opportunity.
I found myself applying several of its elements and structure often throughout the years. Then I took the Dale Carnegie Sales Training course. It's a bit similar to SPIN, however it focuses more on the value of what you're selling; and how to get prospects to see that value. Like SPIN, you lead prospects to seeing the value for themselves, but the Dale Carnegie Approach I find to be more applicable to more situations. Especially when it finds room to understand the buyer's true motivation of wanting to purchase your product or service.
To sum it up, the DC approach seems more genuine and less formulaic. When I used the SPIN techniques, I always felt like a stereotypical "salesman" but when I learned and began applying the DC approach, I felt I was just being honest with my prospects.