The only Purebred dogs I have been around in my life have had problems.
My sister had 2 ex show Pekingnese (different breeders, same rescue) and both died Suddenly. My brothers dog has numerous issues, the golden retriever up the road had a hip replacement at 6 months old.. the list goes on.
While I don't think you should purposely Breed Crossbreeds you should definately only Breed Healthy Purebreeds.
Kimba is a cross and we have only owned Crossbreeds.
As much as I have a soft Spot for certain PBs it would be sheer luck I got the one I am after (bull terrier)
After adopting Kimba from the rspca there's no way I would pay someone for Breeding any dog. IMO theres enough dogs out there already and I'll take one that really needs a second chance.