I'll start out by saying 1) Cousteau was such an awful puppy that I'm just now, 17 years later, thinking maybe all puppies aren't evil incarnate and 2) I had very few border collie puppies in my puppy classes. Typically the ones we had only got into class because there was something wrong and the humans we already really far over their heads with the dog and we had lots of remedial problems to deal with.
My good friend adopted what we are pretty sure is a smooth border collie or a mix that highly border collie. The dog was dumped in rural Tennessee, was pulled from a busy unlimited access shelter, and sent north via Pilots for Paws or whatever that group is. He was just under 4 months old or so when he got into foster care, according to the number of teeth he was losing. He's been to 3 different vets - rescue's, foster's, and my friend's - and all vets have declared him healthy as part of the basic check ups.
This dog is freakishly good. He's got excellent dog skills, which doesn't surprise me a ton if he was on a farm with a lot of dogs and even if he wasn't, the dogs he was with in foster care are excellent for puppies. He gravitates toward kids and is appropriate. He doesn't do a lot of mouthing or nipping, which actually worries me a touch because I want him to learn his jaw strength, but as he gets more comfortable he's mouthing a bit more so I feel better. After a 15-20 minute walk in the morning and 15-20 minutes of stop and go play with my dogs he's ready to chill on the couch for a few hours, then gets the same in the evening. He's not perfect - he jumped out of a 3 ft expen and found stuffed animals to mouth on (thankfully not destroy!), has a thing for shoes, and forgets to let my friend know that he has to pee from time to time, but that's all minor puppy stuff.
He's about 5 months old now, so I know he's still a baby, but he just seems sooooooo chill for a puppy, especially a border collie puppy. Thinking back Havana and Pixel weren't terrors compared to Cousteau, but that's a pretty high bar he set. Pixel was my easiest puppy and I attributed that to having older kids and Havana to nanny him.
Basically, just reassure me that my friend hasn't adopted Cujo who will rip out his throat while he sleeps one night when he hits 2 years old or something.
I am trying to keep in mind that the dog has had a boatload of changes in the past month and he's probably still in his honeymoon phase. I just don't want his good behavior now to suppress exploring he needs to do in order to be a stable adult. I know that sounds kind of weird. I guess I've been a dog trainer for too long!