The sticky at the top of the forum does contain a wealth of information regarding the different hunter specs.
I would point out that on November 13th, this will all likely change. It probably won't stabilize until mid-late January if the expansion to the Burning Crusade was any indicator. So even the sticky is not overly relevant at the moment.
If your son wants to experiment with what SV is right now, today, use the sticky and play with the specification. If he doesn't want to start something and only have it change in a few weeks, then I would recommend he stay with whatever he is comfortable now. Get the best gear he can in a few short weeks (if he's level 70) and get ready to move on from 70 to 80.
We all have a lot of levelling to do!