I see the value in having to struggle to do well. I think it's good preparation for real life.
One of my kids skipped two grades. The second skip (over 5 to 6) was hard. The middle school environment was different and I had to spend a lot of time with him to help him maintain Bs. To be honest, I expected Cs, and was pleasantly surprised when his first report card came in with Bs and a couple As. But homework was a huge struggle. At the same time, he was also advancing in an extracurricular sport, and he had to struggle to learn some new moves. For a while, he despaired that he'd never be able to do an X in this sport, but he persevered and eventually did.
By 7th grade, he only needed about 10% as much help as he'd needed the previous year, and he ended the year with 5 As, plus he got the math award and a few of the teachers gushed about what a wonderful student he was. He'd also advanced a few more levels in that sport.
In his case, the struggling was a good thing. It helped him start to internalize the idea that perseverance is a key to succeeding when things don't come to him right away.
I'm not trying to say that I'd throw one of my kids into sixth grade when he was clearly only ready for fifth. That's different! As weird as the idea of a second skip seemed, it just seemed pretty clear at the time that elementary school didn't have much more to offer him. So we made the decision to put him into an environment where he wouldn't be the top student.
The assumption going into the second skip was that it would be hard for a while, but he'd adapt, eventually perform well, and would be better off for the struggle he had survived.
