That depends upon who you talk to and what your personal philosophy is regarding the sort of terminal performance you are after.
I have not yet shot live game with any of my 6.5's. When I do, I intend to use Berger Hunting VLD's or Hornady AMAX's with my Swede. I don't believe that the Swede develops enough velocity to make tougher bullets necessary. I look forward to testing that theory in the field when my circustances permit.
For my faster 6.5's, I am developing shorter ranged loads with 140g Partitions and long range loads using AMAX's.