From what I've read, if your horse breaks to pacey, longer toes in front and shorter toes in back will help prevent paceyness. Opposite for horses that break to trot.
I judge how well I do by how pronounced her nod is and how fast she can be pushed without breaking to paceyness. (unequal 4 beat). To aid in maintaining 4 equal beats at a faster speed, I'm told to lengthen her toes and shorten her hind toes. It never seems to work as well as keeping an Average length of toe in all 4 hooves, or even having the hind toes slightly longer than front toes.
So, is this a theory, a guideline , a fact? My horse is sickle hocked (hind legs stand more underneath the horse). How much does this have to do with it?