Thanks for the info Corey. I'll be looking into your links shortly.
I found a guy named Dom (I believe in Australia) who has a huge write up on all things related to kefir, and gives information that the live kefir he offers is a combination of something like 15 cultures he's come across in the past.
So far, from what info I've been able to gather, I'm guessing his strain is probably the most diverse I've run across.
Other than Dom, can anyone suggest where to find known biologically diverse kefir starter?