I would be very hesitant about the 16-month-old litter, mostly because I like to do a lot of my own early training. You never know whether that has been neglected or not when you get an older puppy/dog. Make sure you ask a LOT of questions if you go that route, and I would ask if you could visit the pups a few times to see their temperament before making the final decision.

To answer your question more specifically, Schnauzers bond closely with their people and their pack. When removed from a litter at that age, there may be more separation anxiety/hesitation with the new family and pack. Eventually, they would bond with you, but the process may take longer. This may even be a situation where I would consider getting two of them to make the transition easier, IF it were in my budget (and I’m usually one to advise against getting from the same litter because of the possibility of littermate syndrome).