I would have to say that it depends on what the QH is crossed with and what you are planning on doing with it. We are going Thursday to look at a Belgain/QH cross for hubby. She is a dun and absolutely stunning. Although I must admit, I have a soft spot for drafts. But she is only 16.1 and built whereas a purebred would probably 17hh or more. (a friend has a Belgian gelding who is 19hh) One that big would be too difficult for hubby to get on and off of. (he has bad knees) So basically, I would say, it depends.
BTW I didn't see anything wrong with the Arab/Percheron cross. The draft might possibly cool down some of the arabs flightiness. No insult to Arab lovers (my personal riding horse is an arab) but if that filly is trained nicely I could see a lot of people wanting one. JMHO