The number of cores may have to do with your insurance provider. Mine (a big national company) will only allow 6. Just 6. Someone said it was old school, but they still only pay 6, old or new.
Now, on the other hand, my uro is aggressive, and did 12 anyway. At the time I didn't know anything about it, so I did what he said to do. It caused quite an insurance battle, and in the end, Bostwick wrote off the costs for the extra 6 as a courtesy to me. It would have been a very expensive issue if they had not.
So don't be angry with the uro until you know the circumstances.