[Shetland]

I'm looking into getting a new dog, and have heard great things about Yorkies. I've also heard they are angry, yappy, and difficult to housebreak. As you can probably guess, I have a Sheltie currently. How do you think a Yorkie puppy would adapt to growing up with a well-trained Sheltie? Can Yorkies be trained to not bark? If you have owned a Sheltie in the past, or even currently, I would greatly appreciate comparisons between the two. In short, I am looking for general advice on Yorkies, specifically on loudness (which would unfortunately be a deal-breaker), how good they are with other dogs, and also descriptions of them in relation to Shelties (if possible).