Meh. I think it is entirely dependant on what you are trying to do, and what you actually have in your system. 64gig seems to be the magic number for me. Reducing the ram to 6x8gig sticks (48gig) does mean 2000+ additional points in a geekbench score but Pro Tools and OSX runs noticeably worse. I reckon the priority should be first and foremost having enough ram to do what you need to do, and that should include the ability to load a whole lot of stuff into the disk cache in Pro Tools, plus whatever VIs if you are still pulling data from USB2, SATA II HDDs or Firewire.
Give it a spin running it both ways and see how it pans out.
