Homeschooling was the best decision for us. Grade accelerations seem to work for about half the year and then my DD was back at the same level of boredom. We started with the younger DD earlier and for motivated kids, it works out great. We are able to work at the level that they need for different subjects and allow them to explore a lot more options. If we mistakenly move to fast, we just stop and review for a week. Much easier to do when you are already working over a year ahead anyway.
We plan to homeschool until High School. The good thing if you start early is that you can figure out whenever you want if you want to officially grade accelerate or not. We are waiting until High School because high school is more flexible with what a student can take in a certain grade level and there is always AP and Dual Enrollment.
