I think at the end of the day you look at all three: Pedigree, Type, Performance, I do however know an Australian trainer that has two advisor's one looks purely at pedigree the other on type. As for temperament well some believe a lot of that comes from the mare, even though it is well documented around certain stallions/lines so that is an assessment made on pedigree or knowing said stallion.
This year I have taken pedigree advice from someone I respect and although there were several choices of stallion I have chosen the ones that complement the mares physically but....then the phenotype/genotype equation comes in - complicated really. No magic bullet otherwise every breeder would be producing Group1 winners. I'll let you know how I get on.
Regards