As far as the ruseness and breed discrimination... my old trainer had a breeding stock paint who did 3rd level dressage. he moves like a warmblood. Dont let it get to you... I think sometimes when people see a horse doing a discipline that isnt common for the breed, and doing it well, they are a little jelous and don't like to see the horse do well. It's silly... I think sometimes too especially with dressage the big warmblood people feel like "lesser" horses are leaking into their sport. It's all stupid... enjoy your horse, and what makes her a great horse is her talent in the discipline, not her breeding. Do what she likes and what she is good at, and ignore everyone else.
"The white horse moved like a dancer, which is not surprising: a horse is a beautiful animal, but it is perhaps most remarkable because it moves as if it always hears music."