My puppies, now 6 months old, did not enjoy the knots as much as other toys when they were teething. First, the knots were too big for a good chew. Second, the milk teeth would sort of hook the fibers, probably uncomfortable and surely frustrating to the puppies. However, now with adult teeth, knots are among their favorite toys. I bought puppy-sized kongs and nylabones, but no fabric toys. Of course the puppies considered my arms fair game, too.
When I wanted advice, I also felt more comfortable in small specialty stores when I was shopping for the pups. Now I am okay with big-box pet supply stores.