Oh, Fi, I envy you with the pups at that age. They are just so much fun and it's so interesting watching the personalities develop. I just love it when all our puppies line up waiting for their food; nothing cuter. But OMG, the mess, riiiiight? It's a full time job keeping after them.
Yes, you will miss them terribly when they leave for their new home, but I have found that keeping one really helps. No matter how many litters Kris and I breed in our lifetime, I don't think I'll ever get over the sadness when they leave. The only thing that makes it bearable are the happy people coming to take their puppy home forever.