The only objections I see as possibly legit are the ones about your child not being able to read the problems and the one about grades not doing subjects at the same times. I can see how logistically, that could be a little hard. If your DD can already read some, perhaps she will be caught up enough to read the math sheets for gr 1? There usually isn't a lot of text or high-level text.
DS's teachers have worked really hard to have him go between the grades and not miss anything fun or special in his home grade (missing content is not a concern in either grade). It's been a labor of love on their parts, and I really appreciate it. They do teach their math/reading blocks at the same time. I believe this is in place to permit this kind of thing.
