What a great question. I own 8 rescue Yorkies and 1 Biewer "Little Man" and I do see a difference in the 2 personalities of my crew. My Little Man is much more of a clown and wants to just play with everyone. He will share anything and I have never heard him growl but at night when he thinks the bogey man is after man.
I have been in a room with over 10 Biewers and they were all like this with no fighting what so ever. I was surprised to see 3 showdog males getting along so great. They seem to really enjoy people and other pets. Something I cannot always say about Yorkies - they seem to be a little more aggressive at times (geez my little 4# would go after anything it seems
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I love each personality of my dogs but the Biewers just seem to be a little more mello and easy going.
Hope this helps you in your decision.