I have considered this question many times and actually started sort of testing suspended leather saddles. I find absolutely no consistency with the Brooks butt perch. But I do like the saddles A LOT!

The most comfortable was a brand new (four or five years ago) Brooks B17 Special in Honey leather. Comfortable right out of the box and stayed that way to this day. Another time I tried a Brooks B15 from the mid seventies. The saddle was near mint and had seen very little use. And I was quick to understand why. It was horribly, painfully uncomfortable. I removed that saddle and never mounted it on another bike. Keep in mind that the Brooks B15 is wider than the B17 or Pro models.

And that brings up the Pro. I have bought two brand new one and had a few vintage units from the seventies (still have one or two left). In total, I have ridden four Brooks Professional saddles and I had to go through the discomfort of breaking each one in to the shape of my butt.

You cannot fairly test another person's Brooks, in my opinion. To discover if the myth is a myth, or a reasonably accurate evaluation of the product, you will have to try one out and be prepared to do the break in yourself.

Also, an old already broken is saddle just might reshape to your butt and it might not. Again, you have to give it a try. That said, a sagged or worn out looking saddle, is rarely a good place to start looking for comfort.

Much of the above is my opinion and based on my personal experiences with the Brooks product.