Looking at either off these sets off 16GB ram, the DDR3 2400 has better latency than the DDR3 2666 but im guessing the 2666 will be faster in the long run when overclocked.
If you use intel system, the 1600MHz CL8 or Cl9 will be the better for the long run. If you use AMD Trinity Architecture, yes you are right 2400HZ is best.
So I've picked out everything else. Just ram now. I like the corsair 8-8-8-24 but all I've found is 8g (2x4gb) packs. Will it make a huge different to buy the 9-9-9-24 16gb (2x8gb)?