Hangin Tree Cow Dogs are a composite breed originated by Gary Ericsson and his son Choc, from Border Collie, Aussie (one Aussie, Gary's Hangin Tree Black Bear), Kelpie, and Catahoula. They must be short-haired and must show that they have instinct to work stock to be registered. In my experience, they are about Border Collie sized, tend to be a bit blockier in body and head with impressive muscling when fit, tough and aggressive but also intelligent and friendly to people, and stand up to heat and hard jobs.
My guess is that your dog will be within the normal range for a Border Collie in size but, from the sounds of him already, on the larger size, possibly even more so because he may have hybrid vigor, depending on his sire and dam. Short coats tend to be dominant over rough coats so he could have a short or rough coat but you should already be able to see that.
I liked most every one of them I have met, as long as they were nicely socialized and handled firmly but kindly. But you could say that about many breeds of dogs, couldn't you?
Best wishes with him.
PS - If Nicole Rhodes is on here, or if you know her through FB, you might talk to her. She is one person that I know who has worked with multiple breeds of dogs, including HTCD and Border Collies.
Sue Rayburn - Cleverly disguised as a responsible adult, but not the brightest firefly in the jar.
Celt, Megan, and Dan
"When the chips are down, watch where you step."
"The happiest people don't necessarily have the best of everything. They just make the best of everything." - author unknown