Just about to buy a used Mac Pro 4,1 with the intention of flashing to 5,1 and I'm wondering if I should go for 8 cores after all. When I upgrade the CPUs it will be twice the cost, but CPU prices will probably be lower and availability of used will be greater. A 12 core upgrade might soon be in reach. My original plan was to buy a 2.66 quad core, use it for a while and then upgrade to 6 cores. I can pick up a 2.26 eight core for not much more. Any insights appreciated.