YES. Sharon Saare, who has many years of experience riding, and recently,
fitting, many shapes of horse backs, is on the same side of the fine line in
agreement with your generalization. (She would add "mutton withers".) She
makes the point to her audience, however, that it is misleading to make
generalizations to anyone. I agree with your opinion to a certain extent,
i.e., with the "strongly downhill" part, HOWEVER, readers should NEVER use this
generalization alone to rule out a potential downhill-horse's abilities for
your discipline until you ride it and see/feel how it moves!
I had different saddles sliding forward on downhill QHs. Then I rode a
somewhat-downhill Arabian in a Sport Saddle. That horse can get down and work
at any gait! Her saddle slid BACKWARDS when it slid at all! It all depends on
their ability to carry themselves properly. If a person bought a
strongly-downhill horse, they may be likely to travel "level", especially when
in good or approaching-good physical condition. Do the same for toes-in or
-out or any other slight "defect". If the horse travels straight/well and
doesn't interfere, there will not likely be a problem with performance due to
that.
You should also study conformation of performance winners in the sport you're
in. For short-distance racers, a SLIGHTLY downhill appearance, when you're
studying a standstill profile, is not only acceptable but desirable. I will
not extrapolate that to long-distance until I see proof, however, my experience
tells me it couldn't hurt. In addition, if the readers ride the steep terrain
so often spoken of in this forum, they will likely be using the proper
equipment if their saddles slide at all, i.e., breaststrap & crupper. JMHO,
Bridget Brickson in SE PA