I recently picked up a pair of '07 8000s in 165cm length. I'm 61 years old, 150 lbs, 5'8" and a level 8/9 skier. Just spent 3 weeks in Colorado on them in everything from groomers, to bumps, to 8-10 inches of fresh in the Breck bowls. Very happy with them. Definitely an upper speed limit, but since I ski conservatively for my ability, so that's not an issue.
At 210 lbs and level 6, I would go with a 172. He would grow out of the 165s very soon.