I am now the proud owner of 3 NDG's!
I, personally, would be too nervous to put my goats in with my minis. I have 2 very small mares but I just think around feeding time they would bully the goats. My goats are so passive and sweet btu love their morning grain!
One of my mares will cahse my dogs right out of the field and she gets excited and bucks and kicks in the air, she seems to have a great time but my Labrador is terrified. I would worry even in play she could hurt my goats.
I have recently adopted a barncat and she LOVES the horses, in particular the mare mentioned above and they seem to have a very special bond!
I am sure you could do it on a case by case basis....this is just my input!