Unfortunately many of the big muscled horses that are so desirable in halter class are Impressive bred. Are you looking to breed the horse? If not, there is no reason to not get a HYPP horse, just make sure you get the tests in hand before you buy that it is NN
Nothing wrong with a N/N horse-anything without Impressive in its lineage is N/N as well-no worries of ever having it pop up.
The first horses that everyone notices in my herd are Impressive bred-yeah they have more substance to them but they also KNOW they are awesome and that shows in their prescence.
I'm shocked that you are having a hard time finding a horse that is not N/N. I do know that the Impressive line is really big in the halter ring. I personally own 2 impressive horses and they are much more muscular then the others, they are N/N. I think maybe you are looking in the wrong places. Good luck in your search...