Diversity really means having distinct choices available. Right now, if you look at pedigrees you will see that we have a lot of different combinations of a relatively small number of dogs and only a handful of breeders actively working with what can be called distinct lines. This is bad for the breed and for diversity. A large part in this trend, IMO, is popular sire syndrome and people's desire to breed to top winning or top producing stud dogs instead of working on a long term breeding program.
When you look back at the 87/88 imports and the impact that each of the dogs have had on the breed today, you will see alot of their success has to do with the overall quality of the individual. People are more inclined to use dogs that have more to offer their breeding program then just the pre-fix Avongara in their pedigrees. The dogs that produced quality offspring will show up in pedigrees more than once rather than some who seem to have been used simply for their stripes and then never returned to. Another factor in success is that they were successfully preserved in the Avongara breeding programs because they contributed traits that breeders found appealing. Those small pockets of Avongara help to continue to provide diversity for those us who would like to have something different but do not breed enough to do it all by ourselves.