Sarah2108 - My coach has recently gotten into the Iberian horse "thing" (She is an international competitor and coach). She loves how easy to ride the horses are and prefers them for all her adult amateur students. As such I've been recently exposed to a lot of Iberian horses, mostly Andalusians.
The biggest fault she and I find with these horses is a distinct lack of rhythm. While our warmbloods show tension by falling behind the leg, spooking, picking up annoying habits or bucking the rider off, I have found that the Iberian horses lose their rhythm when they are tense.
This is clearly visible if you watch the YouTube video which shows Fuego's test blended with Totilas' test at the WEG. Fuego quite often loses his rhythm.
Now, because our judging system is based on the German system of training, this causes an issue. It is based all on rhythm, this is the most basic step of the training scale. So when a horse loses the rhythm, they must be heavily penalized because if they do not have the first step of the training scale it is assumed that it cannot have fulfilled any other step (Think - the second step in a staircase cannot exist without the first). And this is where the score difference is seen.
However, these horses do have a lot of traits which make them ten times easier to ride than warmbloods. Until the breeders fix the glaring rhythm issues then for a seriously competitive rider, the purchase of a warmblood will remain the best option.
They say money doesn't buy happiness -- well happiness doesn't buy horses!