Interesting, but more marketing than science.
Gaited horses range in way of going from a broken trot to a broken pace. And I have multiple examples of multiple ways of going. To postulate that the adjective "gaited" can then be defined by one, very specific, tree design is not supported by the evidence in my pasture.
I am not unique. Some breeds, like the Paso Fino and Peruvian Paso, have a fairly tight breed standard and a relatively narrow range of diversity in conformation and way of going. "Narrow diversity" does not equal "no diversity." A breed like the TWH, which has no breed standard, has incredible diversity in conformation and way of going. The breed standard of the Marchador is clear and even when you've got a high degree of confomity to that breed standard will also have a some diversity in conformation. Three different ways of going* are permitted. Saying that one, "gaited", tree design will for work for all is not supported by the reality in the paddock.
The back of a pacer and a trotter will work somewhat differently. I'm not sure that difference is sufficient to justify the claims for "unique" tree designs. Further, the padding system one uses is an integral, and important, part of the puzzle. Some say that you don't correct a deficient tree fit with a pad. As a broad statement this is true. But the back of a horse is a dynamic, not a static, environment. Way too many "saddle fitters" don't seem to understand this. The pad, as the interface between the back and the tree, accommodates the motion of the back and keeps weight effectively distributed.
There's nothing wrong with having a custom saddle built for a specific horse. That will normally give a very good fit across a range of motion. But even here there is no guarantee of "perfect fit at all times." Horses gain or lose weight; their weight can shift about as they either "harden" with exercise or "gain condition" in a pasture. A rider whose seat is defective can cause the most perfectly fitted saddle to have pressure points and sore up a back.
The correct fit of a tree is important as it's the "foundation" of the process. But as a foundation is not house, neither is a tree a saddle. There is MUCH more involved.
*Marcha Batida, a broken trot; Marcha Picada, a broken pace; Center March, an insochronal four beat gait.