I would suggest you read the sections on getting a cavalier here on the forum. I wish I had known about his forum before I got my first cavalier (but I was totally ignorant then).
No matter how much this person loves, babies and cares for their dogs, by no means does this mean these two dogs fit to be bred unless they meet the minimum requirements that Pauline already stated. Ethical breeders who show their dogs usually only breed show quality dogs that also pass the health tests. This is to protect the breed standard as well as your future pet from heart-breaking hereditary ailments, your pocketbook from thousands in vet bills, and your heart from the anguish of losing a pet FAR too soon, or watch it spend its days suffering as many on this board have had to, or are having to do. Not only that, it sends a MUCH needed message to these backyard breeders that noone wants their puppies without these minimum standards being met: cardiologist test, the minimum age requirement being met, and, if possible, scans for syringomyelia or the chiari malformation. They need to breed responsibly if they want to find homes for their dogs.
If you still feel comfortable getting the puppy, I'd caution you to let him/her stay for the socialization. There is just no substitute. I got Bandit at 8 weeks, and he was okay, plus with 3 other dogs in the home, he was not dog-less. They continually corrected his behavior. Lizzie came home at 10 weeks. I truthfully didn't see much maturity difference in Lizzie versus Bandit, though there was much better control with her pottying than his. I'd never take a pup younger than 8 weeks, and preferably closer to 10 weeks. (they eat better, sleep better, control their bowels and bladder better)
Good luck!