One of the strengths of the kindergarten setup was the pretend play involved, like the store you used as an example in your post. This is fun, interesting and involves some roles for the students that may be more difficult and allows for a bit of differentiation.

What we found is that in 1st grade those elements go away. So even though Kinder didn't match for pace of instruction needed, it was bearable and still fun for the child. In 1st was where the boredom and suffering from poor fit began.

What I would suggest is making a decision the best you can tell now, with the idea in mind that after 6 weeks or so of school in the fall you will call another meetings to discuss if it is working.

Hope that helps!