Go back into AQHA history , there is an old stud name OLE APP and Ole Roan or Roanie. As with the origination of the breed it was a horse that could run the quarter mile.. hence the name. And I did not say it was Restricted to Appys , it is more commonly used as term for appys. ALso my bad... grulla the hairs are basically all the same color and not a mixture of colors as the roans.
Do you have any unclipped summer coat photos? I would lean toward blue roan (definitely not grullo) because roans get dark in the winter and tend to look a competely different color than their normal roany self. But I would like to see what he looks like in a summer coat first.