I had a wonderful discussion with CTY about this topic.
Our son (8th grade at the time) missed qualifying for their summer program by just a couple of points when looking at the 8th grade requirements. He qualified handily as a 7th grader and I asked if they would consider that he would really be in 6th grade if we had options other than acceleration.
But the CTY program mgr was a stickler on the grade-level, explaining that as an 8th grader, he had all the additional exposure, etc.
Fortunately, he had unsolicited glowing letters from two former CTY instructors explaining that he was ahead of the curve in their courses so she made an exception for one summer with a requirement that he take additional testing to qualify in the future. He subsequently took the SAT at the end of the year and hit his numbers... so all is good.
BUT.
I read about all the GT kids who, instead of skipping, stay with their age-peers but then get carted all over creation for individual subject acceleration in everything except PE and Pottery. These kids get all the same acceleration in the core subjects (or more) as our son, but continue to be tested along side and compared to their age-peers.
This, to me, is no different than a GT kid in a GT class where his age-peers are all doing Geometry and other above-level work in 7th grade. This is essentially the program I had in school, but is simply not available out here in Podunkia, USA.
So, yes, I can see a disadvantage to the skip, but as I mentioned a couple days ago, I couldn't imagine for a second putting him back two or three grades to be with his age-peers. This just means he's gonna have to work a little harder in the next few years... which was kinda the whole point in skipping him!