We did the EXACT same thing. Our son was ready for K at 4, so we put ourselves on a waiting list for the dual immersion and figured we'd homeschool if it didn't come through. Four days before school started, we got a phone call that there was a spot for him, so we took it.
He liked K and I figured we weren't going to homeschool. Loved the teacher and liked the school. Right after his K graduation, on our way home, he expressed, "Mom, can I not go back to school? I hate it." WHAT??? We put him in summer school at a Montessori school nearby, just as a transition, so he would think that changing schools was normal, in the event we decided to homeschool.
(The one thing we really liked about the dual immersion is that our son reads at a 12 grade level and he just turned 9, so he should be in 3rd grade. He learned to read and write Spanish first, so he can pronounce everything....and his accent is awesome. We go to Mexico regularly and he speaks Spanish with me - I only took 4 years of it - and others. They speak to him like he's fluent because his accent is so fluent.)
Well, we decided to HS and he LOVED it. I'd ask him on a regular basis if he wanted to go back to school. "No way!" was always his reply. We put in the hours the state recommends and we were done in 2 months with first grade. What???? I must have missed something. I went back over everything, tested him on everything....nope, we had finished 1st grade in 2 months! So, we moved on to 2nd grade and significantly slowed down the hours we put in and he finished 2nd grade in 7 months. We now put in about an hour a day, so he doesn't get too much further ahead. As we are now, he'll graduate high school at 16...and if he ever decides to back to school, I don't want a boy who is 3 or 4 years younger than those girls...so we are sticking to our minimal schedule.
Trust me, if HSing isn't working, she won't have missed much, if you put her back in school. What got me to completely decide to HS, was research I read that showed the kids only get 2 hours and 13 minutes of actual instruction time. So recess, coming in and out of the classroom, lunch, busy work, etc. I figured I could do better for my son. He's thriving and we belong to 2 great HS groups. The dual immersion was good for ONE year, but more than that....not so sure. My other kids don't sit and do homework like our oldest, who is the only one to be in a formal classroom setting.
I do have a friend who would NEVER HS, but she finally pulled her DD out of school at Christmas break and never went back. Then at the end of the year, she pulled her DS and turns out she is THE biggest HS advocate you can imagine. LOL