I actually LOVE Labradoodles and think they provide the best of both breeds. I know the difference between a mutt and a purebred but I am also not so shallow to walk around describing any animal as a "purebred" even if they are... because it really doesn't matter and by saying so, it sounds like one is being a purebred snob.
As far as temperament, you can get a poor temperament from a purebred or a mutt.... it just depends on so many other factors at play. When you really sit down and think about it, every dog breed has pros and cons.
I have a designer/ hybrid dog. My son brought her home and of course, he quickly realized he didn't have the time he thought he would for her..... so... she started shadowing me around and quickly became my dog.
I had been wanting another dog and in some ways so was my husband but I think we were just hoping one would knock on our door... kinda the same way we ended up with 2 of our cats and 1 of our dogs.
Anyway, back to my hybrid dog. She's a 2 year old Bugg and a cross between a Pugg and a Boston Terrier but unlike a Labradoodle, you really cannot be sure how some hybrids will turn out and a Bugg is a prime example of my point. As you can see in this link, they can be of various colors; some with ears up; some more Pug; some more Boston;
http://www.dogbreedinfo.com/buggs.htm
I didn't set out to have a certain kind of dog. I just wanted one to click in our life and this one does.
My girl is brindle in color and seems to be a perfect cross of a Pugg and Boston. We just love her to pieces.