I'm a non-professional type. Suppose I was looking for a 'sporthorse' and I came to look at your horse. Then you tell me he is a Quarter Horse. I'd probably be polite, mumble some excuse, and leave. Why? Because I would have lost confidence in your integrity. From my non-jumping, non-dressage perspective, if I'm going to lease a horse, I would rate honesty by the owner as critical, and run from anyone giving me bad vibes.
OTOH, if you advertised him as a QH who shows a lot of potential in jumping, built like a sporthorse...then you've told me the facts and I can decide if I'm interested.
Or, to use tlkng1's definition, advertise him as a QH whose conformation and temperament make him an ideal candidate for "the traditional Olympic equestrian sporting events of dressage, eventing, show jumping, and combined driving".