SPD is also interchangable between the sets. I doubt whether there is a whole of difference. They are just warrantied to a higher voltage, that makes the difference. When you are buying a lot of the expensive memories you are paying for the increase in voltage that is warrantied.
Generally speaking get the highest voltage you can afford, as you can set your own timings/speeds to as high as you can go.
Generally speaking get the highest voltage you can afford, as you can set your own timings/speeds to as high as you can go.