My oldest one Muppy is a Shih Tzu/Papillon mix and surely that´s in her character too LOL! She can be very on distance like Shih Tzus are, and it takes a lil´ time before she likes you, but at the other hand she also can be very warm, nice and social, especially to other pets, but IF she´s getting mad, you´ll surely see her Papillon side, teeheeh! She´s not a barker.
My Jack was sold as a Shih Tzu to his former owners, but clearly is that he´s a Shih Tzu/Maltese mix! Jack has the warm character of a Shih Tzu, and also he has the social character, but at the other hand he can be very barkative sometimes, as he doesn´t likes some men, but he´s very social to kids and he loves kids actually! Another thing he has from a Maltese is the fact he can be really ADHD like, working on your nerves and he can be as stubborn as a Shih Tzu, sometimes completely not listening at all and only putting down his own willing.
And Jimmy? Well ... He´s Jack & Jessy´s son and allthough he´s for 80 per cent a Shih Tzu, his character sometimes is also quite Jack-like LOL! 
I think it´s okay there are pure breeds with pedigree, but in my opinion it doesn´t guarantee you a healthy and in character a nice doggy and surely my opinion is that it sometimes is maybe even better to bring a simular kinda breed into the line to forecome diseases and agressive/dominant lines 