Just want to chime in here -
There is a lovely long yearling filly in my barn, she is by of a Dutch WB stallion out of a decent breeding stock QH mare. The mare was QH looking but did not look like a “stock QH” - was uphill and clean. The filly was bred for color - she is, IIRC, genetically a sooty buckskin? IDK. She looks like a grulla to me.
The filly looks just like a QH. Small horse with a big QH jowl, has the “piggy” eye you see in halter bred QHs - but does not move like a stock horse. She moves like a nice leggy TB would with decent suspension and good uphill movement. Unimpressive to look at otherwise.
The breeders had bred her to sell – no one bought her, and my cheap fellow boarder bought her from the west for the fantastic sum of $800 IIRC. I can’t imagine that was a good deal for the breeder.
So no, if you were breeding to sell, I wouldn’t do it. There is a niche market for nice appendix foals, and there is a great market for warmbloods. I can’t imagine the two together would be very profitable.