The breed impressive is a halter horse. They were bred for big bodies, getting muscle quick. You will find out that either people like them or don't. The quarter horse association is going to not let people register there horses if they are positive. I have a quarter horse that is fourteen and his father is impressive, first generation, one of the last one bred. I am lucky he is N/N but there alot of people out there that have positive/ negative and that is bad, alot of the horses that are that end up having a short life expectancy. If it is negative/positive alot of times it is much more controlled and they can live a normal life but you definitely don't want to breed one that has that. If you need more information, just type up
www.answers.com/topic/impressive - I really like the information from here and it explains things well. Good luck, impressive bred horses are beautiful.