I know they still consider them a height breed but since the registry is closed to all but foals of amhr registered parents or aspc shetlands who do meet height requirements and a inspection by a steward (if I remember correctly) or amha registered horses by paying the hardshipping fee. They have a full breed standard and full lists of disqualifications. In most opinions they are a breed now and not just having to meet a height requirement. If the registry still stood open to any horse that met the height requirement and paid the hardship fees, I would agree with you.
As far as if the horse going over the 38" and losing its papers, yes I would still say it is a mini. BUT if the horse were to be sold I would list it as a grade pony and not advertise as a mini horse. A mini horse to me can only be advertised and sold as a mini if it contains papers to prove so. Posted via Mobile Device