Great question Vicky!
There is a tool you can use to calculate the Wright's co-efficient in litters based off of this website. The tool is an indicator of how closely related the parents are.
My own philosophy - I'd love to receive some critiques, advice on this - there are some really high quality dogs that have been bred heavily on (recently). All of my dogs have some of those lines (Amur/Ali, in particular), so from here out I will try to diversify away from those lines somewhat, speaking personally. Of course, since it is such a young breed, there is only a certain amount of diversification you can do - for instance all dogs will have a certain amount of Rep's genes from the earlier era. It takes a lot of research into dog's pedigrees to see what unusual lines you can find in older generations, which has to be balanced out with temperament, health, working ability, and conformation within the line - and also keeping an eye out on what the progeny turns out like in new generations. It's very important to me not to cross heavily on lines that have produced health problems or temperament problems, in particular. Of course it's important to have standard, well formed dogs also - and some traits (like good movement, bite, etc...) are essential - but if the dog will be disabled by age 5 or 6 from HD (or something else), or inapproachable because of shyness or aggression, the rest seems
not quite as important to me.
This is where it becomes VERY important to visit Europe and meet dogs from different breeders and countries, to see the WHOLE dog - personality and all. Even better is to be able to meet siblings and other relatives as well, to see what traits are common among the litter/line - and more likely to be passed along genetically, so you can breed for, or against those traits. There are big differences between dogs, the more detailed a "picture" you can get, the better.
And of course, as distant Americans, we say a prayer that people in other countries with more access to different studs will also continue to breed for diversity.
Marcy