@mrsfeatherbottom, congratulations you lucky thing! I had a Wheaten years ago - fantastic little dogs. We got ours after waiting 18 months on the Breed Club’s Puppy Register and then going through a really comprehensive assessment by the breeder to see if she approved of us, which thankfully she did.
I would say the only downside to them is coat care, as they do need a lot, even with regular groomer visits they will need to be brushed and combed out daily, as although they don’t shed, the coat tangles easily and will felt and be painful really quickly if not properly maintained. The British coat also soaks up water like cotton wool, which can be a pain to deal with. The breed club used to sell a video and run a course on grooming/trimming your own dog, which I did and that made it so much easier.
Contrary to popular belief (a lot of people think they are just batshit crazy hooligans) they are smart little cookies who respond well to positive training. Mine loved to train, she did heelwork to music, agility and obedience, plus loved learning all manner of tricks. She was also loved by everybody she met and an absolute tart who would happily abandon me in a heartbeat to be adored by her fans. My PIL’s used to beg us to let her go caravanning with them as she was always the belle of the campsite and people would constantly ask where she was if she didn’t go with them. 
We lost her when she was 14 and a half. Still miss her and could never have another, as it would be so hard to have a similar looking dog that wasn’t her.
OP, our Wheaten was the only dog we’ve ever bought (the rest have been rescues). She was from a large litter and the breeders house was immaculate and smelt super fresh and clean. All pups were clean, lively and happy, as was Mum. We saw the whelping/bedding area, plus where they were in their playpen (with lots of toys and different surfaces to walk on and climb through etc) as well as most of the downstairs of the house, as we walked through to see them, no dirt or smell anywhere. Even after we’d been approved, the breeder went through another massive questionnaire with us on our first visit to see the puppies and had a very strict contract and whole puppy booklet and pack telling us how to take care of her when we first brought her home. Plus of course lifetime back-up and if anything ever happened, our pup was to go back to her.
As I say, that is my only experience with a breeder vs rescue to date, but I would always expect similar if I was to get another pedigree breed.(Which we are planning to do next time, in fact we are already in contact with the breeder and have been for over a year now, despite not being ready for a pup yet.)