Answer: Percherons are so heavyset that I wouldn't think a cross between a Percheron and a Thoroughbred would produce a very good jumping horse. However, mixed breeds produce all sorts of conformations and abilities, so I can't say that all Percheron/Thoroughbred mixes would be bad. If you're considering breeding the two, I would advise against it; but if you've already got such a horse, then your best bet would be to let a professional take a look at it and give you his or her opinion about its suitability for jumping. You never know, it may work out just fine.