Plus you lose half your equity right off the bat and you are dependent on someone and you aren't really sure what they're going to do for you.
VCs and investors are the only ones who like co-founders because then they can fire one of you that will later on if you're not doing what they want.
In particular, stuff like digging beneath requirements & feature requests to understand the root cause and their current behavior. And probably also the general idea of opening up a safe space for open learning at the beginning of each conversation (which is also a common idea in other sales approaches like SPIN Selling).
Also, it would be more useful while scoping out a new product/market, and less useful for products that are already mature/defined.
So my guess is that you'd get a couple useful ideas, but not a book's worth.
I tried getting my co-founder (a serious old-skool sales guy) to read it, but he refused because he didn't need to be told anything about sales. Then he made exactly all the mistakes you talk about in the book when talking to our prospects. It was my first clue that maybe having a good salesperson as co-founder wasn't going to be the great experience I was anticipating. 2 years later the project died because we didn't get any customers.
I recommend the book to everyone now. If they don't immediately go "this is awesome!" then I'm suspicious ;)